Business Segment Information The Company is managed based on the primary products it manufactures: pulp and wood products. Accordingly, the Company's four pulp mills and its 50% interest in the NBSK pulp mill are aggregated into the pulp business segment, and the Friesau mill is a separate reportable business segment, wood products. The Company's sandalwood business is included in Corporate and Other as it does not meet the criteria to be reported as a separate segment. None of the income or loss items following operating income in the Company's Consolidated Statement of Operations are allocated to the segments, since those items are reviewed separately by management. Information about certain segment data for the years ended December 31, 2018, 2017 and 2016, was as follows: December 31, 2018 Pulp Wood Products Corporate and Other Consolidated Revenues from external customers $ 1,268,204 $ 189,036 $ 478 $ 1,457,718 Operating income (loss) $ 274,356 $ 6,203 $ (12,692 ) $ 267,867 Depreciation and amortization $ 87,628 $ 8,485 $ 616 $ 96,729 Purchase of property, plant and equipment $ 66,207 $ 20,682 $ 123 $ 87,012 Total assets (1) $ 1,698,071 $ 131,754 $ 145,910 $ 1,975,735 Revenues by major products Pulp $ 1,190,588 $  $  $ 1,190,588 Lumber  168,663  168,663 Energy and chemicals 77,616 10,831 478 88,925 Wood residuals  9,542  9,542 Total revenues $ 1,268,204 $ 189,036 $ 478 $ 1,457,718 Revenues by geographical markets U.S. $ 55,692 $ 52,770 $  $ 108,462 Germany 499,620 73,854  573,474 China 291,657   291,657 Other countries 421,235 62,412 478 484,125 Total revenues $ 1,268,204 $ 189,036 $ 478 $ 1,457,718 (1) Total assets for the pulp segment includes the Company's $62,574 investment in the 50% owned NBSK pulp mill. December 31, 2017 Pulp Wood Products Corporate and Other Consolidated Revenues from external customers $ 1,071,715 $ 97,430 $  $ 1,169,145 Operating income (loss) $ 171,279 $ 5,610 $ (8,335 ) $ 168,554 Depreciation and amortization $ 80,833 $ 4,060 $ 401 $ 85,294 Purchase of property, plant and equipment $ 54,534 $ 3,197 $ 184 $ 57,915 Total assets $ 1,253,545 $ 116,320 $ 354,845 $ 1,724,710 Revenues by major products Pulp $ 979,645 $  $  $ 979,645 Lumber  82,176  82,176 Energy and chemicals 92,070 8,872  100,942 Wood residuals  6,382  6,382 Total revenues $ 1,071,715 $ 97,430 $  $ 1,169,145 Revenues by geographical markets U.S. $ 23,572 $ 20,060 $  $ 43,632 Germany 421,895 47,146  469,041 China 292,231   292,231 Other countries 334,017 30,224  364,241 Total revenues $ 1,071,715 $ 97,430 $  $ 1,169,145 December 31, 2016 Pulp Wood Products Corporate and Other Consolidated Revenues from external customers $ 931,623 $  $  $ 931,623 Operating income (loss) $ 124,594 $  $ (9,470 ) $ 115,124 Depreciation and amortization $ 71,476 $  $ 508 $ 71,984 Purchase of property, plant and equipment $ 42,462 $  $ 64 $ 42,526 Revenues by major products Pulp $ 847,328 $  $  $ 847,328 Lumber     Energy and chemicals 84,295   84,295 Wood residuals     Total revenues $ 931,623 $  $  $ 931,623 Revenues by geographical markets U.S. $ 26,985 $  $  $ 26,985 Germany 401,802   401,802 China 221,773   221,773 Other countries 281,063   281,063 Total revenues $ 931,623 $  $  $ 931,623 Revenues between segments are accounted for at prices that approximate fair value. These include revenues from the sale of residual fiber from the wood products segment to the pulp segment for use in the pulp production process and from the sale of residual fuel from the pulp segment to the wood products segment for use in energy production. For the year ended December 31, 2018, the pulp segment sold $1,343 of residual fuel to the wood products segment (2017  $1,350 ) and the wood products segment sold $18,537 of residual fiber to the pulp segment (2017  $12,697 ). The following table presents total long-lived assets by geographic area based on location of the asset: December 31, 2018 2017 Germany $ 655,260 $ 681,141 Canada 355,817 163,707 Australia 18,180  $ 1,029,257 $ 844,848 In 2018 , one customer for the pulp segment through several of their operations accounted for 13% of the Companys total revenues ( 2017  one customer through several of their operations accounted for 13% ; 2016  two customers through several of their operations accounted for 19% and 10% ).