Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
|  |  | Year Ended December 31, | Year Ended December 31, | Year Ended December 31, |
| --- | --- | --- | --- | --- |
|  |  | 2019 | 2018 (a) | 2017 (a) |
| Operating revenue: | Passenger revenue | $39,625 | $37,706 | $34,460 |
| Operating revenue: | Cargo | 1,179 | 1,237 | 1,114 |
| Operating revenue: | Other operating revenue | 2,455 | 2,360 | 2,210 |
| Operating revenue: | Total operating revenue | 43,259 | 41,303 | 37,784 |
| Operating expense: | Salaries and related costs | 12,071 | 11,458 | 10,941 |
| Operating expense: | Aircraft fuel | 8,953 | 9,307 | 6,913 |
| Operating expense: | Regional capacity purchase | 2,849 | 2,649 | 2,268 |
| Operating expense: | Landing fees and other rent | 2,543 | 2,449 | 2,310 |
| Operating expense: | Depreciation and amortization | 2,288 | 2,165 | 2,096 |
| Operating expense: | Aircraft maintenance materials and outside repairs | 1,794 | 1,767 | 1,856 |
| Operating expense: | Distribution expenses | 1,651 | 1,558 | 1,435 |
| Operating expense: | Aircraft rent | 288 | 433 | 621 |
| Operating expense: | Special charges | 246 | 487 | 176 |
| Operating expense: | Other operating expenses | 6,275 | 5,801 | 5,550 |
| Operating expense: | Total operating expense | 38,958 | 38,074 | 34,166 |
| Operating expense: | Operating income | 4,301 | 3,229 | 3,618 |
| Nonoperating income (expense): | Interest expense | ( 731 ) | ( 670 ) | ( 626 ) |
| Nonoperating income (expense): | Interest capitalized | 85 | 65 | 74 |
| Nonoperating income (expense): | Interest income | 133 | 101 | 57 |
| Nonoperating income (expense): | Unrealized gains (losses) on investments, net | 153 | ( 5 ) | — |
| Nonoperating income (expense): | Miscellaneous, net | ( 27 ) | ( 72 ) | ( 100 ) |
| Nonoperating income (expense): | Total nonoperating expense, net | ( 387 ) | ( 581 ) | ( 595 ) |
| Nonoperating income (expense): | Income before income taxes | 3,914 | 2,648 | 3,023 |
| Nonoperating income (expense): | Income tax expense | 905 | 526 | 880 |
| Nonoperating income (expense): | Net income | $3,009 | $2,122 | $2,143 |
| Nonoperating income (expense): | Earnings per share, basic | $11.63 | $7.70 | $7.08 |
| Nonoperating income (expense): | Earnings per share, diluted | $11.58 | $7.67 | $7.06 |
Question:
How much income tax did United Airlines pay in 2017?
Answer:
$2,143