CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Millions	Total	Series A Preferred Stock	Common stock	Common stock Class B common stock	Additional paid-in capital	Additional paid-in capital Series A Preferred Stock	Treasury stock	Retained earnings (deficit)	Accumulated other comprehensive income (loss)	Non-redeemable non-controlling interest
Beginning balance (in shares) at Dec. 31, 2019			256,691,777	12,799,999			126,892,525
Beginning balance at Dec. 31, 2019	$ 5,536		$ 0	$ 0	$ 12,978		$ (9,673)	$ 879	$ (217)	$ 1,569
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(2,137)							(2,037)		(100)
Other comprehensive income (loss), net of taxes	(56)								(56)
Payment of preferred dividends	(17)				(17)
Payment of dividends to common stockholders	(48)							(48)
Proceeds from exercise of equity instruments and employee stock purchase plans (in shares)			2,393,155
Proceeds from exercise of equity instruments and employee stock purchase plans	96				96
Common stock warrants, net of issuance costs	110				110
Treasury stock activity related to vesting of equity instruments (in shares)							(393,099)
Treasury stock activity related to vesting of equity instruments	$ (44)						$ (44)
Common stock repurchases (in shares)	3,400,000						3,364,119
Common stock repurchases	$ (370)						$ (370)
Adjustment to the fair value of redeemable non-controlling interests	4				4
Other changes in ownership of non-controlling interests	10				10
Stock-based compensation expense	118				118
Other	1				1
Other (in shares)							20,630
Ending balance (in shares) at Jun. 30, 2020			259,084,932	12,799,999			130,670,373
Ending balance at Jun. 30, 2020	3,203		$ 0	$ 0	13,300		$ (10,087)	(1,206)	(273)	1,469
Beginning balance (in shares) at Mar. 31, 2020			258,769,812	12,799,999			130,592,112
Beginning balance at Mar. 31, 2020	3,741		$ 0	$ 0	13,124		$ (10,083)	(470)	(301)	1,471
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(740)							(736)		(4)
Other comprehensive income (loss), net of taxes	34								28	6
Payment of preferred dividends	(17)				(17)
Proceeds from exercise of equity instruments and employee stock purchase plans (in shares)			315,120
Proceeds from exercise of equity instruments and employee stock purchase plans	10				10
Common stock warrants, net of issuance costs	110				110
Treasury stock activity related to vesting of equity instruments (in shares)							57,631
Treasury stock activity related to vesting of equity instruments	(4)						$ (4)
Adjustment to the fair value of redeemable non-controlling interests	4				4
Other changes in ownership of non-controlling interests	5				9					(4)
Stock-based compensation expense	59				59
Other	1				1
Other (in shares)							20,630
Ending balance (in shares) at Jun. 30, 2020			259,084,932	12,799,999			130,670,373
Ending balance at Jun. 30, 2020	3,203		$ 0	$ 0	13,300		$ (10,087)	(1,206)	(273)	1,469
Beginning balance (in shares) at Dec. 31, 2020			261,563,912	12,799,999			130,766,537
Beginning balance at Dec. 31, 2020	3,004		$ 0	$ 0	13,566		$ (10,097)	(1,781)	(178)	1,494
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(758)							(750)		(8)
Other comprehensive income (loss), net of taxes	(18)								(8)	(10)
Payment of preferred dividends	(50)	$ (50)			(50)
Proceeds from exercise of equity instruments and employee stock purchase plans (in shares)			5,204,899
Proceeds from exercise of equity instruments and employee stock purchase plans	379				379
Exercise of common stock warrants (in shares)			2,470,221
Loss on redemption of preferred stock		(107)				$ (107)
Withholding taxes for stock options	(7)				(7)
Treasury stock activity related to vesting of equity instruments (in shares)							551,881
Treasury stock activity related to vesting of equity instruments	$ (85)						$ (85)
Common stock repurchases (in shares)	0
Adjustment to the fair value of redeemable non-controlling interests	$ (11)				(11)
Other changes in ownership of non-controlling interests	10				0					10
Stock-based compensation expense	225				225
Ending balance (in shares) at Jun. 30, 2021			269,239,032	12,799,999			131,318,418
Ending balance at Jun. 30, 2021	2,582		$ 0	$ 0	13,995		$ (10,182)	(2,531)	(186)	1,486
Beginning balance (in shares) at Mar. 31, 2021			265,207,012	12,799,999			131,141,343
Beginning balance at Mar. 31, 2021	2,688		$ 0	$ 0	13,919		$ (10,152)	(2,359)	(199)	1,479
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(177)							(172)		(5)
Other comprehensive income (loss), net of taxes	19								13	6
Payment of preferred dividends	(50)				(50)
Proceeds from exercise of equity instruments and employee stock purchase plans (in shares)			1,561,799
Proceeds from exercise of equity instruments and employee stock purchase plans	110				110
Exercise of common stock warrants (in shares)			2,470,221
Loss on redemption of preferred stock		$ (107)				$ (107)
Treasury stock activity related to vesting of equity instruments (in shares)							177,075
Treasury stock activity related to vesting of equity instruments	(30)						$ (30)
Adjustment to the fair value of redeemable non-controlling interests	(11)				(11)
Other changes in ownership of non-controlling interests	6				0					6
Stock-based compensation expense	134				134
Ending balance (in shares) at Jun. 30, 2021			269,239,032	12,799,999			131,318,418
Ending balance at Jun. 30, 2021	$ 2,582		$ 0	$ 0	$ 13,995		$ (10,182)	$ (2,531)	$ (186)	$ 1,486