| Consolidated Statements of Stockholders' Equity - USD ($)shares in Millions, $ in Millions
 | Total | Common Stock | Treasury Stock | Additional Paid-in Capital | Accumulated Deficit | Non-controlling Interest | 
| Common Stock, Shares, Outstanding, Beginning of Period at Dec. 31, 2019 | 253.6 |  |  |  |  |  | 
| Treasury Stock, Shares, Beginning of Period at Dec. 31, 2019 | 17.1 |  |  |  |  |  | 
| Stockholders' Equity, Beginning of Period at Dec. 31, 2019 | $ 2,435 | $ 1 | $ (674) | $ 4,167 | $ (3,508) | $ 2,449 | 
| Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |  |  | 
| Vesting of restricted stock units and performance stock units, shares |  | 2.1 | 0.0 |  |  |  | 
| Vesting of restricted stock units and performance stock units | 0 | $ 0 | $ 0 | 0 | 0 | 0 | 
| Share-based compensation | 29 | $ 0 | $ 0 | 29 | 0 | 0 | 
| Issued shares withheld from employees related to share-based compensation, at cost, shares, common stock |  | (0.7) |  |  |  |  | 
| Issued shares withheld from employees related to share-based compensation, at cost, shares, treasury shares |  |  | 0.7 |  |  |  | 
| Issued shares withheld from employees related to share-based compensation, at cost | (39) | $ 0 | $ (39) | 0 | 0 | 0 | 
| Shares repurchased, at cost, shares |  | (2.9) | 2.9 |  |  |  | 
| Shares repurchased, at cost | (155) | $ 0 | $ (155) | 0 | 0 | 0 | 
| Net income attributable to non-controlling interest | 228 | 0 | 0 | 0 | 0 | 228 | 
| Distributions to non-controlling interest | (154) | 0 | 0 | 0 | 0 | (154) | 
| Net income | $ 375 | 0 | 0 | 0 | 375 | 0 | 
| Common Stock, Shares, Outstanding, End of Period at Mar. 31, 2020 | 252.1 |  |  |  |  |  | 
| Treasury Stock, Shares, End of Period at Mar. 31, 2020 | 20.7 |  |  |  |  |  | 
| Stockholders' Equity, End of Period at Mar. 31, 2020 | $ 2,719 | 1 | (868) | 4,196 | (3,133) | 2,523 | 
| Common Stock, Shares, Outstanding, Beginning of Period at Dec. 31, 2019 | 253.6 |  |  |  |  |  | 
| Treasury Stock, Shares, Beginning of Period at Dec. 31, 2019 | 17.1 |  |  |  |  |  | 
| Stockholders' Equity, Beginning of Period at Dec. 31, 2019 | $ 2,435 | 1 | (674) | 4,167 | (3,508) | 2,449 | 
| Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |  |  | 
| Net income attributable to non-controlling interest | 435 |  |  |  |  |  | 
| Net income | $ 572 |  |  |  |  |  | 
| Common Stock, Shares, Outstanding, End of Period at Jun. 30, 2020 | 252.2 |  |  |  |  |  | 
| Treasury Stock, Shares, End of Period at Jun. 30, 2020 | 20.7 |  |  |  |  |  | 
| Stockholders' Equity, End of Period at Jun. 30, 2020 | $ 2,996 | 1 | (870) | 4,227 | (2,936) | 2,574 | 
| Common Stock, Shares, Outstanding, Beginning of Period at Mar. 31, 2020 | 252.1 |  |  |  |  |  | 
| Treasury Stock, Shares, Beginning of Period at Mar. 31, 2020 | 20.7 |  |  |  |  |  | 
| Stockholders' Equity, Beginning of Period at Mar. 31, 2020 | $ 2,719 | $ 1 | $ (868) | 4,196 | (3,133) | 2,523 | 
| Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |  |  | 
| Vesting of restricted stock units and performance stock units, shares |  | 0.1 | 0.0 |  |  |  | 
| Vesting of restricted stock units and performance stock units | 0 | $ 0 | $ 0 | 0 | 0 | 0 | 
| Share-based compensation | 31 | $ 0 | $ 0 | 31 | 0 | 0 | 
| Issued shares withheld from employees related to share-based compensation, at cost, shares, common stock |  | 0.0 |  |  |  |  | 
| Issued shares withheld from employees related to share-based compensation, at cost, shares, treasury shares |  |  | 0.0 |  |  |  | 
| Issued shares withheld from employees related to share-based compensation, at cost | (2) | $ 0 | $ (2) | 0 | 0 | 0 | 
| Net income attributable to non-controlling interest | 207 | 0 | 0 | 0 | 0 | 207 | 
| Distributions to non-controlling interest | (156) | 0 | 0 | 0 | 0 | (156) | 
| Net income | $ 197 | 0 | 0 | 0 | 197 | 0 | 
| Common Stock, Shares, Outstanding, End of Period at Jun. 30, 2020 | 252.2 |  |  |  |  |  | 
| Treasury Stock, Shares, End of Period at Jun. 30, 2020 | 20.7 |  |  |  |  |  | 
| Stockholders' Equity, End of Period at Jun. 30, 2020 | $ 2,996 | 1 | (870) | 4,227 | (2,936) | 2,574 | 
| Common Stock, Shares, Outstanding, Beginning of Period at Dec. 31, 2020 | 252.3 |  |  |  |  |  | 
| Treasury Stock, Shares, Beginning of Period at Dec. 31, 2020 | 20.8 |  |  |  |  |  | 
| Stockholders' Equity, Beginning of Period at Dec. 31, 2020 | $ 2,218 | $ 1 | $ (872) | 4,273 | (3,593) | 2,409 | 
| Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |  |  | 
| Vesting of restricted stock units and performance stock units, shares |  | 1.8 | 0.0 |  |  |  | 
| Vesting of restricted stock units and performance stock units | 0 | $ 0 | $ 0 | 0 | 0 | 0 | 
| Share-based compensation | 33 | $ 0 | $ 0 | 33 | 0 | 0 | 
| Issued shares withheld from employees related to share-based compensation, at cost, shares, common stock |  | (0.6) |  |  |  |  | 
| Issued shares withheld from employees related to share-based compensation, at cost, shares, treasury shares |  |  | 0.6 |  |  |  | 
| Issued shares withheld from employees related to share-based compensation, at cost | (42) | $ 0 | $ (42) | 0 | 0 | 0 | 
| Net income attributable to non-controlling interest | 178 | 0 | 0 | 0 | 0 | 178 | 
| Distributions to non-controlling interest | (160) | 0 | 0 | 0 | 0 | (160) | 
| Net income | $ 393 | 0 | 0 | 0 | 393 | 0 | 
| Common Stock, Shares, Outstanding, End of Period at Mar. 31, 2021 | 253.5 |  |  |  |  |  | 
| Treasury Stock, Shares, End of Period at Mar. 31, 2021 | 21.4 |  |  |  |  |  | 
| Stockholders' Equity, End of Period at Mar. 31, 2021 | $ 2,620 | 1 | (914) | 4,306 | (3,200) | 2,427 | 
| Common Stock, Shares, Outstanding, Beginning of Period at Dec. 31, 2020 | 252.3 |  |  |  |  |  | 
| Treasury Stock, Shares, Beginning of Period at Dec. 31, 2020 | 20.8 |  |  |  |  |  | 
| Stockholders' Equity, Beginning of Period at Dec. 31, 2020 | $ 2,218 | 1 | (872) | 4,273 | (3,593) | 2,409 | 
| Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |  |  | 
| Net income attributable to non-controlling interest | 376 |  |  |  |  |  | 
| Net income | $ 64 |  |  |  |  |  | 
| Common Stock, Shares, Outstanding, End of Period at Jun. 30, 2021 | 253.6 |  |  |  |  |  | 
| Treasury Stock, Shares, End of Period at Jun. 30, 2021 | 21.4 |  |  |  |  |  | 
| Stockholders' Equity, End of Period at Jun. 30, 2021 | $ 2,357 | 1 | (915) | 4,337 | (3,529) | 2,463 | 
| Common Stock, Shares, Outstanding, Beginning of Period at Mar. 31, 2021 | 253.5 |  |  |  |  |  | 
| Treasury Stock, Shares, Beginning of Period at Mar. 31, 2021 | 21.4 |  |  |  |  |  | 
| Stockholders' Equity, Beginning of Period at Mar. 31, 2021 | $ 2,620 | $ 1 | $ (914) | 4,306 | (3,200) | 2,427 | 
| Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |  |  | 
| Vesting of restricted stock units and performance stock units, shares |  | 0.1 | 0.0 |  |  |  | 
| Vesting of restricted stock units and performance stock units | 0 | $ 0 | $ 0 | 0 | 0 | 0 | 
| Share-based compensation | 31 | $ 0 | $ 0 | 31 | 0 | 0 | 
| Issued shares withheld from employees related to share-based compensation, at cost, shares, common stock |  | 0.0 |  |  |  |  | 
| Issued shares withheld from employees related to share-based compensation, at cost, shares, treasury shares |  |  | 0.0 |  |  |  | 
| Issued shares withheld from employees related to share-based compensation, at cost | (1) | $ 0 | $ (1) | 0 | 0 | 0 | 
| Net income attributable to non-controlling interest | 198 | 0 | 0 | 0 | 0 | 198 | 
| Distributions to non-controlling interest | (162) | 0 | 0 | 0 | 0 | (162) | 
| Net income | $ (329) | 0 | 0 | 0 | (329) | 0 | 
| Common Stock, Shares, Outstanding, End of Period at Jun. 30, 2021 | 253.6 |  |  |  |  |  | 
| Treasury Stock, Shares, End of Period at Jun. 30, 2021 | 21.4 |  |  |  |  |  | 
| Stockholders' Equity, End of Period at Jun. 30, 2021 | $ 2,357 | $ 1 | $ (915) | $ 4,337 | $ (3,529) | $ 2,463 |