pre_text: The following table reconciles total segment adjusted EBITDA to net (loss) income for the years ended December 31, 2019, 2018 and 2017: We do not have any single customer that provides more than 10% of our consolidated total operating revenue. The assets we hold outside of the U.S. represent less than 10% of our total assets. Revenue from sources outside of the U.S. is responsible for less than 10% of our total operating revenue.
table: Years Ended December 31,
table: 2019 2018 2017
table: (Dollars in millions)
table: Total segment adjusted EBITDA $15,987 16,647 12,560
table: Depreciation and amortization (4,829) (5,120) (3,936)
table: Goodwill impairment (6,506) (2,726) —
table: Other operating expenses (7,216) (8,045) (6,504)
table: Share-based compensation (162) (186) (111)
table: Operating (loss) income (2,726) 570 2,009
table: Total other expense, net (2,040) (2,133) (1,469)
table: (Loss) income before income taxes (4,766) (1,563) 540
table: Income tax expense (benefit) 503 170 (849)
table: Net (loss) income $(5,269) (1,733) 1,389
question: Analyse this data from a financial earnings document. What is the sum of income tax expense (benefit) in 2018 and 2019?