Segment Reporting The Company's reportable operating segments include Established Communities, Other Stabilized Communities and Development/Redevelopment Communities. Annually as of January 1, the Company determines which of its communities fall into each of these categories and generally maintains that classification throughout the year for the purpose of reporting segment operations, unless disposition or redevelopment plans regarding a community change.  Established Communities (also known as Same Store Communities) are consolidated communities where the Company has a significant presence (New England, New York/New Jersey, Mid-Atlantic, Pacific Northwest, and Northern and Southern California) and where a comparison of operating results from the prior year to the current year is meaningful, as these communities were owned and had stabilized occupancy as of the beginning of the prior year. The Established Communities for the year ended December 31, 2018 , are communities that are consolidated for financial reporting purposes, had stabilized occupancy as of January 1, 2017 , are not conducting or planning to conduct substantial redevelopment activities and are not held for sale or planned for disposition within the fiscal year. A community is considered to have stabilized occupancy at the earlier of (i) attainment of 95% physical occupancy or (ii) the one -year anniversary of completion of development or redevelopment.  Other Stabilized Communities includes all other completed consolidated communities that have stabilized occupancy, as defined above, as January 1, 2018 , or which were acquired during the year ended December 31, 2018 . Other Stabilized Communities includes stabilized operating communities in our expansion markets of Denver, Colorado, and Southeast Florida, but excludes communities that are conducting or planning to conduct substantial redevelopment activities within the fiscal year.  Development/Redevelopment Communities consists of (i) consolidated communities that are either currently under construction, or were under construction during the fiscal year, which may be partially or fully complete and operating, (ii) consolidated communities where substantial redevelopment is in progress or is planned to begin during the fiscal year and (iii) communities under lease-up that have been complete for less than one year and have not reached stabilized occupancy, as defined above, as of January 1, 2018 . In addition, the Company owns land for future development and has other corporate assets that are not allocated to an operating segment. The Company's segment disclosures present the measure(s) used by the chief operating decision maker for purposes of assessing each segment's performance. The Company's chief operating decision maker is comprised of several members of its executive management team who use net operating income (NOI) as the primary financial measure for Established Communities and Other Stabilized Communities. NOI is defined by the Company as total property revenue less direct property operating expenses (including property taxes), and excluding corporate-level income (including management, development and other fees), corporate-level property management and other indirect operating expenses, investments and investment management expenses, expensed transaction, development and other pursuit costs, net of recoveries, interest expense, net, loss (gain) on extinguishment of debt, net, general and administrative expense, equity in income of unconsolidated real estate entities, depreciation expense, corporate income tax (benefit) expense, casualty and impairment loss (gain), net, gain on sale of communities, loss (gain) on other real estate transactions, net and net operating income from real estate assets sold or held for sale. Although the Company considers NOI a useful measure of a community's or communities' operating performance, NOI should not be considered an alternative to net income or net cash flow from operating activities, as determined in accordance with GAAP. NOI excludes a number of income and expense categories as detailed in the reconciliation of NOI to net income. A reconciliation of NOI to net income for years ended December 31, 2018 , 2017 and 2016 is as follows (dollars in thousands): For the year ended 12/31/18 12/31/17 12/31/16 Net income $ 974,175 $ 876,660 $ 1,033,708 Indirect operating expenses, net of corporate income 76,522 65,398 61,403 Investments and investment management expense 7,709 5,936 4,822 Expensed acquisition, development and other pursuit costs, net of recoveries 4,309 2,736 9,922 Interest expense, net 220,974 199,661 187,510 Loss on extinguishment of debt, net 17,492 25,472 7,075 General and administrative expense 56,365 50,673 45,771 Equity in income of unconsolidated real estate entities (15,270 ) (70,744 ) (64,962 ) Depreciation expense 631,196 584,150 531,434 Income tax (benefit) expense (160 ) 141 305 Casualty and impairment loss (gain), net 215 6,250 (3,935 ) Gain on sale of communities (374,976 ) (252,599 ) (374,623 ) (Gain) loss on other real estate transactions (345 ) 10,907 (10,224 ) Net operating income from real estate assets sold or held for sale (58,620 ) (84,650 ) (114,219 ) Net operating income $ 1,539,586 $ 1,419,991 $ 1,313,987 The following is a summary of NOI from real estate assets sold or held for sale for the periods presented (dollars in thousands): For the year ended 12/31/2018 12/31/2017 12/31/2016 Rental income from real estate assets sold or held for sale $ 88,865 $ 133,956 $ 179,226 Operating expenses from real estate assets sold or held for sale (30,245 ) (49,306 ) (65,007 ) Net operating income from real estate assets sold or held for sale $ 58,620 $ 84,650 $ 114,219 The primary performance measure for communities under development or redevelopment depends on the stage of completion. While under development, management monitors actual construction costs against budgeted costs as well as lease-up pace and rent levels compared to budget. The following table provides details of the Company's segment information as of the dates specified (dollars in thousands). The segments are classified based on the individual community's status at January 1, 2018 for the years ended December 31, 2018 and 2017 and at January 1, 2017 , for the year ended December 31, 2016 . Segment information for the years ended December 31, 2018 , 2017 and 2016 has been adjusted to exclude the real estate assets that were sold from January 1, 2016 through December 31, 2018 , or otherwise qualify as held for sale as of December 31, 2018 , as described in Note 6, Real Estate Disposition Activities. Total revenue NOI Gross real estate (1) For the year ended December 31, 2018 Established New England $ 239,638 $ 157,109 $ 2,014,158 Metro NY/NJ 360,430 254,132 3,086,133 Mid-Atlantic 237,113 165,724 2,226,315 Pacific Northwest 86,571 62,194 727,652 Northern California 366,834 280,994 2,986,068 Southern California 341,840 245,356 2,921,616 Total Established (2) 1,632,426 1,165,509 13,961,942 Other Stabilized 262,053 178,172 2,934,711 Development / Redevelopment 297,619 195,905 5,201,454 Land Held for Future Development N/A N/A 84,712 Non-allocated (3) 3,572 N/A 94,350 Total $ 2,195,670 $ 1,539,586 $ 22,277,169 For the year ended December 31, 2017 Established New England $ 232,688 $ 152,514 $ 1,993,653 Metro NY/NJ 354,444 251,760 3,071,563 Mid-Atlantic 232,987 161,546 2,216,292 Pacific Northwest 84,313 61,705 724,751 Northern California 357,209 273,940 2,972,311 Southern California 330,024 237,796 2,905,512 Total Established (2) 1,591,665 1,139,261 13,884,082 Other Stabilized 193,594 127,678 2,571,356 Development / Redevelopment (4) 235,266 153,052 4,104,956 Land Held for Future Development N/A N/A 68,364 Non-allocated (3) 4,147 N/A 78,864 Real estate disposed or held for sale (5) 1,228,314 Total $ 2,024,672 $ 1,419,991 $ 21,935,936 For the year ended December 31, 2016 Established New England $ 209,935 $ 136,019 $ 1,667,171 Metro NY/NJ 294,199 204,882 2,412,742 Mid-Atlantic 203,003 141,624 1,862,091 Pacific Northwest 79,958 57,857 731,277 Northern California 331,610 253,582 2,812,859 Southern California 313,404 224,955 2,840,773 Total Established (2) 1,432,109 1,018,919 12,326,913 Other Stabilized 221,272 151,475 2,650,966 Development / Redevelopment (6) 207,049 143,593 4,154,778 Land Held for Future Development N/A N/A 84,293 Non-allocated (3) 5,599 N/A 80,700 Real estate disposed or held for sale (5) 1,458,130 Total $ 1,866,029 $ 1,313,987 $ 20,755,780 _________________________________ (1) Does not include gross real estate assets held for sale of $65,408 and $20,846 as of December 31, 2018 and 2016 , respectively. (2) Gross real estate for the Company's Established Communities includes capitalized additions of approximately $78,469 , $78,241 and $85,676 in 2018 , 2017 and 2016 , respectively. (3) Revenue represents third-party management, accounting, and developer fees and miscellaneous income which are not allocated to a reportable segment. (4) Total revenue and NOI for the year ended December 31, 2017 includes $3,495 in business interruption insurance proceeds related to the Maplewood casualty loss. (5) Represents real estate sold or held for sale between the reported year end date and December 31, 2018, which is not allocated to a reportable segment. (6) Total revenue and NOI for the year ended December 31, 2016 includes $20,306 in business interruption insurance proceeds related to the Edgewater casualty loss.