total debt at december 31 , 2017 and 2016 consisted of $ 1.50 billion of senior notes . during the second quarter 2017 , we repaid our 5.875 % $ 750 million notes due 2022 and issued 3.90 % $ 750 million notes due 2027 . our 4.375 % $ 750 million notes are due 2024 . cash on hand at december 31 , 2017 was $ 400.5 million . for the year ended december 31 , 2017 , we had net income of $ 494.3 million ( $ 5.19 per diluted share ) , as compared to a net loss of $ 408.8 million ( $ 4.38 per diluted share ) in 2016 . production revenue in 2017 was positively impacted by increased realized commodity prices and production volumes . lower commodity prices negatively impacted 2016 , including resulting in $ 757.7 million of impairments of our oil and gas properties in that year . year-over-year changes are discussed further in the results of operations section that follows . proved reserves our proved reserves by region at december 31 , 2017 and 2016 were as follows : replace_table_token_17_th replace_table_token_18_th 35 year-end 2017 proved reserves increased approximately 16 % to 3.35 tcfe , compared to 2.89 tcfe at year-end 2016 . proved gas reserves were 1.61 tcf , proved oil reserves were 0.82 tcfe , and proved ngl reserves were 0.92 tcfe . reserves in our mid-continent region accounted for 52 % of total proved reserves with nearly all of the remainder in the permian basin . during 2017 , we added 940.7 bcfe of new reserves through extensions and discoveries . net negative revisions totaled 59.7 bcfe , which consisted primarily of a decrease of 248.8 bcfe for the removal of pud reserves whose development will likely be delayed beyond five years of initial disclosure , offset by an increase of 187.2 bcfe related to improved commodity prices . see supplemental information on oil and gas producing activities ( unaudited ) in item 8 for a more detailed discussion regarding year-over-year changes in our proved reserves . the process of estimating quantities of oil , gas , and ngl reserves is complex . significant decisions are required in the evaluation of all available geological , geophysical , engineering , and economic data . although every reasonable effort is made to ensure that our reserve estimates represent the most accurate assessments possible , subjective decisions and available data for our various fields make these estimates generally less precise than other estimates included in financial statement disclosures . see proved reserves estimation procedures in items 1 and 2 for a discussion of our reserve estimation process and item 1a risk factors , which includes a discussion of factors that affect our proved reserves estimates . results of operations 2017 compared to 2016 revenue almost all our revenue is derived from sales of our oil , natural gas , and ngl production . increases or decreases in our revenue , profitability , and future production growth are highly dependent on the commodity prices we receive . prices are market driven and we expect that future prices will continue to fluctuate due to supply and demand factors , seasonality , geopolitical , and economic factors . see item 7a quantitative and qualitative disclosures about market risk for more information regarding the sensitivity of our revenues to price fluctuations . realized prices and production volumes were higher in 2017 as compared to 2016 , which caused our revenue to increase by $ 652.8 million , or 53 % , from the prior year . the following table shows our production revenue for the years indicated as well as the change in revenue due to changes in prices and volumes . replace_table_token_19_th the table below presents our production volumes by commodity , our average realized commodity prices , and certain major u.s. index prices . the sale of our permian basin oil production is typically tied to the wti midland benchmark price and the sale of our mid-continent oil production is typically tied to the wti cushing benchmark price . during 2017 and 2016 , 78 % and 80 % , respectively , of our oil production was in the permian basin and 22 % and 20 % , respectively , was in the mid-continent region . our realized prices do not include settlements of commodity derivative contracts . 36 replace_table_token_20_th our 2017 daily production volumes were 1,142.1 mmcfe , a 19 % increase from 2016 . this increase is the result of increased drilling and completion activity during 2017 as compared to 2016. see production volumes , prices , and costs and exploration and development overview in items 1 and 2 of this report for production information by region and a discussion of our drilling activities . other revenues we transport , process , and market some third-party gas that is associated with our equity gas . we market and sell gas for other working interest owners under short term agreements and may earn a fee for such services . the table below reflects income from third-party gas gathering and processing and our net marketing margin for marketing third-party gas . replace_table_token_21_th fluctuations in revenues from gas gathering and gas marketing activities are a function of increases and decreases in volumes , commodity prices , and gathering rate charges . the increases from 2016 are primarily due to an increase in prices . 37 operating costs and expenses costs associated with producing oil and gas are substantial . among other factors , some of these costs vary with commodity prices , some trend with the volume of production , others are a function of the number of wells we own , and some depend on the prices charged by service companies . total operating costs and expenses of $ 1.17 billion in 2017 were 36 % lower than the $ 1.83 billion incurred in 2016 . story_separator_special_tag we remeasured the deferred tax assets and liabilities as of december 31 , 2017 to reflect the reduction in the u.s. income tax rate from 35 % to 21 % for years after 2017 and , as a result of this remeasurement , we recorded an income tax benefit of $ 61.1 million and a corresponding $ 61.1 million decrease in the net deferred tax liabilities as of december 31 , 2017. we believe the accounting for the effects of h.r.1 recognized in the december 31 , 2017 financial statements is materially complete . however , evolving analyses and interpretations of the law may cause a change to the amounts presented . any such changes that may arise will be recognized in the period determined , but no later than december 31 , 2018. it is not expected any such change will be material to the financial statements . as a result of h.r.1 , we expect our effective tax rate in future periods will be lower than in periods prior to enactment . in addition , the limitations on utilization of net operating losses and deductibility of interest and executive compensation may result in the payment of cash taxes earlier than expected . our combined federal and state effective tax rates differ from the statutory rate of 35 % primarily due to state income taxes , non-deductible expenses , revisions , and the impact of changes in tax law . see note 9 to the consolidated financial statements for further information regarding our income taxes . results of operations 2016 compared to 2015 summary for the year ended december 31 , 2016 , we had a net loss of $ 408.8 million ( $ 4.38 per diluted share ) , down from a net loss of $ 2.58 billion ( $ 27.75 per diluted share ) in 2015 . production revenues in 2016 and 2015 were adversely affected by low realized commodity prices , which also brought about impairments of our oil and gas properties and net losses for each year . although production revenue in 2016 was lower than in 2015 , the decrease was more than offset by lower impairment , dd & a , and other operating costs in 2016 . year-over-year changes are discussed further as follows . also refer to the “ 2017 compared to 2016 ” section above for general information regarding various statement of operations line items . revenue our 2016 production revenue was 14 % lower than that of 2015 . lower realized prices and production volumes for oil and gas were only partially offset by higher realized prices and production volumes for ngls . the following table shows our production revenue for the years indicated as well as the change in revenue due to changes in prices and volumes . replace_table_token_30_th the table below presents our production volumes by commodity , our average realized commodity prices , and certain major u.s. index prices . the sale of our permian basin oil production is typically tied to the wti midland benchmark price and the sale of our mid-continent oil production is typically tied to the wti cushing benchmark price . during 2016 and 2015 , 80 % and 84 % , respectively , of our oil production was in the permian basin and 20 % and 15 % , respectively , was in the mid-continent region . our realized prices do not include settlements of commodity derivative contracts . 43 replace_table_token_31_th other revenues we transport , process , and market some third-party gas that is associated with our equity gas . we market and sell gas for other working interest owners under short term agreements and may earn a fee for such services . the table below reflects income from third-party gas gathering and processing and our net marketing margin for marketing third-party gas . replace_table_token_32_th fluctuations in revenues from gas gathering and gas marketing activities are a function of increases and decreases in volumes , commodity prices , and gathering rate charges . operating costs and expenses total operating costs and expenses of $ 1.83 billion in 2016 were 67 % lower than the $ 5.46 billion incurred in 2015 . most of the decrease resulted from lower ceiling test impairments of our oil and gas properties and lower dd & a expense . the following table shows our operating costs and expenses for the years indicated and a discussion of year-over-year differences follows . 44 replace_table_token_33_th ceiling test impairment during the first three quarters of 2016 , we recognized ceiling test impairments totaling $ 757.7 million ( $ 481.4 million net of tax ) . we recognized ceiling test impairments in 2015 totaling $ 4.03 billion ( $ 2.56 billion net of tax ) . the impairments resulted primarily from the impact of decreases in the trailing twelve-month average prices for oil , gas , and ngls utilized in determining the estimated future net revenues from proved reserves . at december 31 , 2016 , the calculated value of the ceiling limitation exceeded the carrying value of our oil and gas properties subject to the test , and no impairment was necessary . however , a decline of 7 % or more in the value of the ceiling limitation would have resulted in an impairment . depreciation , depletion , and amortization depletion expense in 2016 decreased compared to 2015 due to the quarterly impairments of our oil and gas properties from the first quarter of 2015 through the third quarter of 2016. depletion expense generally decreases following ceiling test impairments due to the decrease in the net proved properties balance . dd & a consisted of the following for the years indicated : replace_table_token_34_th production production costs consist of lease operating expense and workover expense as follows : replace_table_token_35_th lease operating expense in 2016 declined 24 % compared to 2015 . in 2016 , we incurred lower saltwater disposal costs due to implementation of operational efficiencies as well

bank debt below for further information regarding our credit facility . we have made , and will continue to make , expenditures to comply with environmental and safety regulations and requirements . these costs are considered a normal recurring cost of our ongoing operations . while we expect current pending legislation or regulations to increase the cost of business , we do not anticipate that we will be required to expend amounts that will have a material adverse effect on our financial position or operations , nor are we aware of any pending regulatory changes that would have a material impact , based on current laws and regulations . however , compliance with new legislation or regulations could increase our costs or adversely affect demand for oil or gas and result in a material adverse effect on our financial position or operations . see item 1a risk factors for a description of risks related to current and potential future environmental and safety regulations and requirements that could adversely affect our operations and financial condition . 50 long-term debt long-term debt at december 31 , 2017 and 2016 consisted of the following : replace_table_token_43_th ( 1 ) at december 31 , 2017 , the unamortized debt issuance costs and discount related to the 3.90 % notes were $ 5.9 million and $ 1.8 million , respectively . the 4.375 % notes were issued at par . bank debt in october 2015 , we entered into a new senior unsecured revolving credit facility ( “ credit facility ” ) which matures october 16 , 2020. the credit facility has aggregate commitments of $ 1.0 billion , with an option to increase aggregate commitments to $ 1.25 billion at any time . there is no borrowing base subject to the discretion of the lenders based on the value of our proved reserves under the credit facility . as of december 31 , 2017 , we had no bank borrowings outstanding under the credit facility , but did have letters of credit of $ 2.5 million outstanding , leaving an unused borrowing availability of $ 997.5 million .


 Write a concise suspicious activity report of the following text delimited by triple backquotes. Return your response as a formal report which covers the key points highlighting the location,dates,entity names and account holder information in chronological order of the text.
     ```bank debt below for further information regarding our credit facility . we have made , and will continue to make , expenditures to comply with environmental and safety regulations and requirements . these costs are considered a normal recurring cost of our ongoing operations . while we expect current pending legislation or regulations to increase the cost of business , we do not anticipate that we will be required to expend amounts that will have a material adverse effect on our financial position or operations , nor are we aware of any pending regulatory changes that would have a material impact , based on current laws and regulations . however , compliance with new legislation or regulations could increase our costs or adversely affect demand for oil or gas and result in a material adverse effect on our financial position or operations . see item 1a risk factors for a description of risks related to current and potential future environmental and safety regulations and requirements that could adversely affect our operations and financial condition . 50 long-term debt long-term debt at december 31 , 2017 and 2016 consisted of the following : replace_table_token_43_th ( 1 ) at december 31 , 2017 , the unamortized debt issuance costs and discount related to the 3.90 % notes were $ 5.9 million and $ 1.8 million , respectively . the 4.375 % notes were issued at par . bank debt in october 2015 , we entered into a new senior unsecured revolving credit facility ( “ credit facility ” ) which matures october 16 , 2020. the credit facility has aggregate commitments of $ 1.0 billion , with an option to increase aggregate commitments to $ 1.25 billion at any time . there is no borrowing base subject to the discretion of the lenders based on the value of our proved reserves under the credit facility . as of december 31 , 2017 , we had no bank borrowings outstanding under the credit facility , but did have letters of credit of $ 2.5 million outstanding , leaving an unused borrowing availability of $ 997.5 million .
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 Suspicious Activity Report : total debt at december 31 , 2017 and 2016 consisted of $ 1.50 billion of senior notes . during the second quarter 2017 , we repaid our 5.875 % $ 750 million notes due 2022 and issued 3.90 % $ 750 million notes due 2027 . our 4.375 % $ 750 million notes are due 2024 . cash on hand at december 31 , 2017 was $ 400.5 million . for the year ended december 31 , 2017 , we had net income of $ 494.3 million ( $ 5.19 per diluted share ) , as compared to a net loss of $ 408.8 million ( $ 4.38 per diluted share ) in 2016 . production revenue in 2017 was positively impacted by increased realized commodity prices and production volumes . lower commodity prices negatively impacted 2016 , including resulting in $ 757.7 million of impairments of our oil and gas properties in that year . year-over-year changes are discussed further in the results of operations section that follows . proved reserves our proved reserves by region at december 31 , 2017 and 2016 were as follows : replace_table_token_17_th replace_table_token_18_th 35 year-end 2017 proved reserves increased approximately 16 % to 3.35 tcfe , compared to 2.89 tcfe at year-end 2016 . proved gas reserves were 1.61 tcf , proved oil reserves were 0.82 tcfe , and proved ngl reserves were 0.92 tcfe . reserves in our mid-continent region accounted for 52 % of total proved reserves with nearly all of the remainder in the permian basin . during 2017 , we added 940.7 bcfe of new reserves through extensions and discoveries . net negative revisions totaled 59.7 bcfe , which consisted primarily of a decrease of 248.8 bcfe for the removal of pud reserves whose development will likely be delayed beyond five years of initial disclosure , offset by an increase of 187.2 bcfe related to improved commodity prices . see supplemental information on oil and gas producing activities ( unaudited ) in item 8 for a more detailed discussion regarding year-over-year changes in our proved reserves . the process of estimating quantities of oil , gas , and ngl reserves is complex . significant decisions are required in the evaluation of all available geological , geophysical , engineering , and economic data . although every reasonable effort is made to ensure that our reserve estimates represent the most accurate assessments possible , subjective decisions and available data for our various fields make these estimates generally less precise than other estimates included in financial statement disclosures . see proved reserves estimation procedures in items 1 and 2 for a discussion of our reserve estimation process and item 1a risk factors , which includes a discussion of factors that affect our proved reserves estimates . results of operations 2017 compared to 2016 revenue almost all our revenue is derived from sales of our oil , natural gas , and ngl production . increases or decreases in our revenue , profitability , and future production growth are highly dependent on the commodity prices we receive . prices are market driven and we expect that future prices will continue to fluctuate due to supply and demand factors , seasonality , geopolitical , and economic factors . see item 7a quantitative and qualitative disclosures about market risk for more information regarding the sensitivity of our revenues to price fluctuations . realized prices and production volumes were higher in 2017 as compared to 2016 , which caused our revenue to increase by $ 652.8 million , or 53 % , from the prior year . the following table shows our production revenue for the years indicated as well as the change in revenue due to changes in prices and volumes . replace_table_token_19_th the table below presents our production volumes by commodity , our average realized commodity prices , and certain major u.s. index prices . the sale of our permian basin oil production is typically tied to the wti midland benchmark price and the sale of our mid-continent oil production is typically tied to the wti cushing benchmark price . during 2017 and 2016 , 78 % and 80 % , respectively , of our oil production was in the permian basin and 22 % and 20 % , respectively , was in the mid-continent region . our realized prices do not include settlements of commodity derivative contracts . 36 replace_table_token_20_th our 2017 daily production volumes were 1,142.1 mmcfe , a 19 % increase from 2016 . this increase is the result of increased drilling and completion activity during 2017 as compared to 2016. see production volumes , prices , and costs and exploration and development overview in items 1 and 2 of this report for production information by region and a discussion of our drilling activities . other revenues we transport , process , and market some third-party gas that is associated with our equity gas . we market and sell gas for other working interest owners under short term agreements and may earn a fee for such services . the table below reflects income from third-party gas gathering and processing and our net marketing margin for marketing third-party gas . replace_table_token_21_th fluctuations in revenues from gas gathering and gas marketing activities are a function of increases and decreases in volumes , commodity prices , and gathering rate charges . the increases from 2016 are primarily due to an increase in prices . 37 operating costs and expenses costs associated with producing oil and gas are substantial . among other factors , some of these costs vary with commodity prices , some trend with the volume of production , others are a function of the number of wells we own , and some depend on the prices charged by service companies . total operating costs and expenses of $ 1.17 billion in 2017 were 36 % lower than the $ 1.83 billion incurred in 2016 . story_separator_special_tag we remeasured the deferred tax assets and liabilities as of december 31 , 2017 to reflect the reduction in the u.s. income tax rate from 35 % to 21 % for years after 2017 and , as a result of this remeasurement , we recorded an income tax benefit of $ 61.1 million and a corresponding $ 61.1 million decrease in the net deferred tax liabilities as of december 31 , 2017. we believe the accounting for the effects of h.r.1 recognized in the december 31 , 2017 financial statements is materially complete . however , evolving analyses and interpretations of the law may cause a change to the amounts presented . any such changes that may arise will be recognized in the period determined , but no later than december 31 , 2018. it is not expected any such change will be material to the financial statements . as a result of h.r.1 , we expect our effective tax rate in future periods will be lower than in periods prior to enactment . in addition , the limitations on utilization of net operating losses and deductibility of interest and executive compensation may result in the payment of cash taxes earlier than expected . our combined federal and state effective tax rates differ from the statutory rate of 35 % primarily due to state income taxes , non-deductible expenses , revisions , and the impact of changes in tax law . see note 9 to the consolidated financial statements for further information regarding our income taxes . results of operations 2016 compared to 2015 summary for the year ended december 31 , 2016 , we had a net loss of $ 408.8 million ( $ 4.38 per diluted share ) , down from a net loss of $ 2.58 billion ( $ 27.75 per diluted share ) in 2015 . production revenues in 2016 and 2015 were adversely affected by low realized commodity prices , which also brought about impairments of our oil and gas properties and net losses for each year . although production revenue in 2016 was lower than in 2015 , the decrease was more than offset by lower impairment , dd & a , and other operating costs in 2016 . year-over-year changes are discussed further as follows . also refer to the “ 2017 compared to 2016 ” section above for general information regarding various statement of operations line items . revenue our 2016 production revenue was 14 % lower than that of 2015 . lower realized prices and production volumes for oil and gas were only partially offset by higher realized prices and production volumes for ngls . the following table shows our production revenue for the years indicated as well as the change in revenue due to changes in prices and volumes . replace_table_token_30_th the table below presents our production volumes by commodity , our average realized commodity prices , and certain major u.s. index prices . the sale of our permian basin oil production is typically tied to the wti midland benchmark price and the sale of our mid-continent oil production is typically tied to the wti cushing benchmark price . during 2016 and 2015 , 80 % and 84 % , respectively , of our oil production was in the permian basin and 20 % and 15 % , respectively , was in the mid-continent region . our realized prices do not include settlements of commodity derivative contracts . 43 replace_table_token_31_th other revenues we transport , process , and market some third-party gas that is associated with our equity gas . we market and sell gas for other working interest owners under short term agreements and may earn a fee for such services . the table below reflects income from third-party gas gathering and processing and our net marketing margin for marketing third-party gas . replace_table_token_32_th fluctuations in revenues from gas gathering and gas marketing activities are a function of increases and decreases in volumes , commodity prices , and gathering rate charges . operating costs and expenses total operating costs and expenses of $ 1.83 billion in 2016 were 67 % lower than the $ 5.46 billion incurred in 2015 . most of the decrease resulted from lower ceiling test impairments of our oil and gas properties and lower dd & a expense . the following table shows our operating costs and expenses for the years indicated and a discussion of year-over-year differences follows . 44 replace_table_token_33_th ceiling test impairment during the first three quarters of 2016 , we recognized ceiling test impairments totaling $ 757.7 million ( $ 481.4 million net of tax ) . we recognized ceiling test impairments in 2015 totaling $ 4.03 billion ( $ 2.56 billion net of tax ) . the impairments resulted primarily from the impact of decreases in the trailing twelve-month average prices for oil , gas , and ngls utilized in determining the estimated future net revenues from proved reserves . at december 31 , 2016 , the calculated value of the ceiling limitation exceeded the carrying value of our oil and gas properties subject to the test , and no impairment was necessary . however , a decline of 7 % or more in the value of the ceiling limitation would have resulted in an impairment . depreciation , depletion , and amortization depletion expense in 2016 decreased compared to 2015 due to the quarterly impairments of our oil and gas properties from the first quarter of 2015 through the third quarter of 2016. depletion expense generally decreases following ceiling test impairments due to the decrease in the net proved properties balance . dd & a consisted of the following for the years indicated : replace_table_token_34_th production production costs consist of lease operating expense and workover expense as follows : replace_table_token_35_th lease operating expense in 2016 declined 24 % compared to 2015 . in 2016 , we incurred lower saltwater disposal costs due to implementation of operational efficiencies as well

