CONSOLIDATED STATEMENTS OF EQUITY AND REDEEMABLE NONCONTROLLING INTERESTS - USD ($) $ in Millions	Total	Cumulative Effect, Period of Adoption, Adjustment	Class A Common Stock	Class B Common Stock	Common Stock Class A Common Stock	Common Stock Class B Common Stock	Additional Paid-In Capital	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Loss	Noncontrolling Interests
Increase (Decrease) in Temporary Equity
Net income (loss)	$ 0
BALANCE at Dec. 31, 2018	0
BALANCE (in shares) at Dec. 31, 2017					76,071,145	25,670,684
BALANCE at Dec. 31, 2017	1,535	$ 2			$ 1	$ 0	$ 1,321	$ 249	$ 2	$ (2)	$ (34)
Increase (Decrease) in Stockholders' Equity
Dividends declared and paid on Class A and Class B Common Stock	(74)							(74)
Repurchase of Class A Common Stock (in shares)					(7,761,529)
Repurchases of Class A Common Stock	(221)						(221)
Class A Common Stock issued pursuant to employee benefit plans (in shares)					588,107
Class A Common Stock issued pursuant to employee benefit plans	21						21
Distributions to noncontrolling interests, net	(10)										(10)
Other comprehensive income	1									1
Net income (loss)	346							341			5
BALANCE (in shares) at Dec. 31, 2018					68,897,723	25,670,684
BALANCE at Dec. 31, 2018	1,600				$ 1	$ 0	1,121	518		(1)	(39)
Increase (Decrease) in Temporary Equity
Issuance of redeemable subsidiary preferred equity, net of issuance costs	985
Noncontrolling interests issued	380
Distributions to noncontrolling interests, net	(38)
Redemption of redeemable subsidiary preferred equity, net of fees	(297)
Net income (loss)	48
BALANCE at Dec. 31, 2019	1,078
Increase (Decrease) in Stockholders' Equity
Dividends declared and paid on Class A and Class B Common Stock	(73)							(73)
Class B Common Stock converted into Class A Common Stock (in shares)					943,002	(943,002)
Class B Common Stock converted into Class A Common Stock	0
Repurchase of Class A Common Stock (in shares)					(4,555,487)
Repurchases of Class A Common Stock	(145)						(145)
Class A Common Stock issued pursuant to employee benefit plans (in shares)					1,544,872
Class A Common Stock issued pursuant to employee benefit plans	35						35
Noncontrolling interests acquired in a business combination	248										248
Distributions to noncontrolling interests, net	(27)										(27)
Other comprehensive income	(1)									(1)
Net income (loss)	105
Net income (loss)	57							47			10
BALANCE (in shares) at Dec. 31, 2019			66,830,110	24,727,682	66,830,110	24,727,682
BALANCE at Dec. 31, 2019	1,694				$ 1	$ 0	1,011	492		(2)	192
Increase (Decrease) in Temporary Equity
Noncontrolling interests issued	22
Distributions to redeemable noncontrolling interests	(419)
Redemption of redeemable subsidiary preferred equity, net of fees	(547)
Net income (loss)	56
BALANCE at Dec. 31, 2020	190
Increase (Decrease) in Stockholders' Equity
Dividends declared and paid on Class A and Class B Common Stock	(64)							(64)
Repurchase of Class A Common Stock (in shares)					(19,418,934)
Repurchases of Class A Common Stock	(343)						(343)
Class A Common Stock issued pursuant to employee benefit plans (in shares)					1,841,495
Class A Common Stock issued pursuant to employee benefit plans	53						53
Noncontrolling interests acquired in a business combination	0
Distributions to noncontrolling interests, net	(32)										(32)
Other comprehensive income	(8)									(8)
Net income (loss)	(2,429)
Net income (loss)	(2,485)							(2,414)			(71)
BALANCE (in shares) at Dec. 31, 2020			49,252,671	24,727,682	49,252,671	24,727,682
BALANCE at Dec. 31, 2020	$ (1,185)				$ 1	$ 0	$ 721	$ (1,986)		$ (10)	$ 89