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:
|  |  | Common Stock | Common Stock | Additional Capital Invested | Treasury Stock | Retained Earnings (Accumulated Deficit) | Accumulated Other Comprehensive Income (Loss) | Total |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  |  | Shares | Amount |  |  |  |  |  |
| Balance at December 31, 2015 |  | 364.6 | $4 | $7,946 | $(1,610) | $3,457 | $(831) | $8,966 |
| Balance at December 31, 2016 | Net income (a) | — | — | — | — | 2,234 | — | 2,234 |
| Balance at December 31, 2016 | Other comprehensive income | — | — | — | — | — | 2 | 2 |
| Balance at December 31, 2016 | Stock-settled share-based compensation | — | — | 32 | — | — | — | 32 |
| Balance at December 31, 2016 | Proceeds from exercise of stock options | 0.3 | — | 6 | — | — | — | 6 |
| Balance at December 31, 2016 | Repurchases of common stock | (50.3) | — | — | (2,607) | — | — | (2,607) |
| Balance at December 31, 2016 | Treasury stock retired | — | (1) | (1,415) | 3,709 | (2,293) | — | — |
| Balance at December 31, 2016 | Other (a) | — | — | — | (3) | (56) | — | (59) |
| Balance at December 31, 2016 |  | 314.6 | 3 | 6,569 | (511) | 3,342 | (829) | 8,574 |
| Balance at December 31, 2017 | Net income (a) | — | — | — | — | 2,144 | — | 2,144 |
| Balance at December 31, 2017 | Other comprehensive loss | — | — | — | — | — | (200) | (200) |
| Balance at December 31, 2017 | Stock-settled share-based compensation | — | — | 56 | — | — | — | 56 |
| Balance at December 31, 2017 | Proceeds from exercise of stock options | - | — | 2 | — | — | — | 2 |
| Balance at December 31, 2017 | Repurchases of common stock | (27.8) | — | — | (1,844) | — | — | (1,844) |
| Balance at December 31, 2017 | Treasury stock retired | — | - | (508) | 1,576 | (1,068) | — | — |
| Balance at December 31, 2017 | Net treasury stock issued for share-based awards | 0.2 | — | (21) | 10 | (1) | — | (12) |
| Balance at December 31, 2017 | Excess tax benefits from share-based awards | — | — | — | — | 14 | — | 14 |
| Balance at December 31, 2017 | Reclassification of stranded tax effects | — | — | — | — | 118 | (118) | — |
| Balance at December 31, 2017 |  | 287.0 | 3 | 6,098 | (769) | 4,549 | (1,147) | 8,734 |
| Balance at December 31, 2018 | Net income | — | — | — | — | 2,129 | — | 2,129 |
| Balance at December 31, 2018 | Other comprehensive loss | — | — | — | — | — | 338 | 338 |
| Balance at December 31, 2018 | Stock-settled share-based compensation | — | — | 60 | — | — | — | 60 |
| Balance at December 31, 2018 | Repurchases of common stock | (17.5) | — | — | (1,250) | — | — | (1,250) |
| Balance at December 31, 2018 | Net treasury stock issued for share-based awards | 0.4 | — | (38) | 26 | (4) | — | (16) |
| Balance at December 31, 2018 | Adoption of accounting standard related to equity investments | — | — | — | — | (6) | 6 | — |
| Balance at December 31, 2018 |  | 269.9 | $3 | $6,120 | $(1,993) | $6,668 | $(803) | $9,995 |
Question:
How much did United spend on its share repurchase program in 2017?
Answer:
(1,844)