Consolidated Statements of Stockholders' Deficit - USD ($) $ in Millions	Total	Redeemable Noncontrolling Interests (Non- Equity)	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Noncontrolling Interest
Equity, beginning balance at Dec. 31, 2018	$ (1,463)		$ 1	$ 2,017	$ (10)	$ (3,543)	$ 72
Redeemable Noncontrolling Interests, beginning balance at Dec. 31, 2018		$ 504
Shares, outstanding, beginning balance at Dec. 31, 2018			116,248,376
Comprehensive income (loss)	(641)				1	(675)	33
Comprehensive income (loss) attributable to redeemable noncontrolling interest		52
Contributions from noncontrolling interests	7						7
Contributions from redeemable noncontrolling interests		3
Distributions to noncontrolling interests	(31)						(31)
Distributions to redeemable noncontrolling interests		(68)
Purchase of subsidiary shares from noncontrolling interests	(3)	(8)		3			(6)
Other reclassifications of noncontrolling interests	2						2
Other reclassifications of redeemable noncontrolling interests		(2)
Adjustment to redemption value of redeemable noncontrolling interests	(21)	21		(21)
Cancellation of restricted stock for tax withholdings on vested shares	(1)			(1)
Cancellation of restricted stock for tax withholdings on vested shares, shares			(298,182)
Income tax payable increase from vesting of restricted shares			333
Stock-based compensation	10			10
Stock-based compensation, shares			1,872,104
Equity, ending balance at Dec. 31, 2019	(2,141)		$ 1	2,008	(9)	(4,218)	77
Redeemable Noncontrolling Interests, ending balance at Dec. 31, 2019		502
Shares, outstanding, ending balance at Dec. 31, 2019			117,822,631
Comprehensive income (loss)	545				(4)	511	38
Comprehensive income (loss) attributable to redeemable noncontrolling interest		58
Contributions from noncontrolling interests	15						15
Distributions to noncontrolling interests	(34)						(34)
Distributions to redeemable noncontrolling interests		(82)
Purchase of subsidiary shares from noncontrolling interests	3	(4)		3
Other reclassifications of noncontrolling interests	(9)						(9)
Other reclassifications of redeemable noncontrolling interests		9
Disposition of less-than-wholly owned hospital		(14)
Adjustment to redemption value of redeemable noncontrolling interests	(15)	15		(15)
Cancellation of restricted stock for tax withholdings on vested shares	(1)			(1)
Cancellation of restricted stock for tax withholdings on vested shares, shares			(288,859)
Issuance of common stock in connection with the exercise of stock options, shares			18,166
Income tax payable increase from vesting of restricted shares			333
Section 3(a)(9) exchange	86			86
Section 3(a)(9) exchange, shares			10,000,000
Stock-based compensation	13			13
Stock-based compensation, shares			2,059,846
Equity, ending balance at Dec. 31, 2020	(1,538)		$ 1	2,094	(13)	(3,707)	87
Redeemable Noncontrolling Interests, ending balance at Dec. 31, 2020	484	484
Shares, outstanding, ending balance at Dec. 31, 2020			129,612,117
Comprehensive income (loss)	266				(2)	230	38
Comprehensive income (loss) attributable to redeemable noncontrolling interest		100
Contributions from redeemable noncontrolling interests		1
Distributions to noncontrolling interests	(39)						(39)
Distributions to redeemable noncontrolling interests		(82)
Purchase of subsidiary shares from noncontrolling interests	13	(32)		17			(4)
Other reclassifications of noncontrolling interests	1				1
Other reclassifications of redeemable noncontrolling interests		1
Disposition of less-than-wholly owned hospital		(7)
Noncontrolling interests in acquired entity		2
Adjustment to redemption value of redeemable noncontrolling interests	(13)	13		(13)
Cancellation of restricted stock for tax withholdings on vested shares	(5)			(5)
Cancellation of restricted stock for tax withholdings on vested shares, shares			(584,379)
Issuance of common stock in connection with the exercise of stock options, shares			65,499
Stock-based compensation	25			25
Stock-based compensation, shares			3,053,045
Equity, ending balance at Dec. 31, 2021	(1,290)		$ 1	$ 2,118	$ (14)	$ (3,477)	$ 82
Redeemable Noncontrolling Interests, ending balance at Dec. 31, 2021	$ 480	$ 480
Shares, outstanding, ending balance at Dec. 31, 2021			132,146,282