Consolidated Statements of Stockholders' Equity - USD ($) $ in Millions	Total	Common Stock	Treasury Stock	Additional Paid-in Capital	Accumulated Income (Loss)	Accumulated Other Comprehensive Income (Loss)	Total	Noncontrolling Interest
Beginning balance (in shares) at Dec. 31, 2017		98,017,860	(157,812)
Beginning balance at Dec. 31, 2017	$ 2,348	$ 1	$ (4)	$ 1,235	$ (112)	$ (26)	$ 1,094	$ 1,254
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Class A common stock under equity incentive award plan, shares		256,809
Issuance of Class A common stock under equity incentive award plan, net	0						0
Repurchase of shares for employee tax withholding, shares			(20,097)
Repurchase of shares for employee tax withholding	0						0
Stock-based compensation	1			1			1
Dividends declared	(42)			(18)	(24)		(42)
Acquisitions	11						0	11
Distributions to noncontrolling interests	(9)						0	(9)
Net income (loss)	(13)				136		136	(149)
Other comprehensive loss, net of tax	(2)					(1)	(1)	(1)
Ending balance (in shares) at Mar. 31, 2018		98,274,669	(177,909)
Ending balance at Mar. 31, 2018	2,294	$ 1	$ (4)	1,218	0	(27)	1,188	1,106
Beginning balance (in shares) at Dec. 31, 2017		98,017,860	(157,812)
Beginning balance at Dec. 31, 2017	2,348	$ 1	$ (4)	1,235	(112)	(26)	1,094	1,254
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Acquisitions	52				0
Distributions to noncontrolling interests	(29)				0
Net income (loss)	(46)
Other comprehensive loss, net of tax	12
Ending balance (in shares) at Sep. 30, 2018		98,274,669	(178,783)
Ending balance at Sep. 30, 2018	2,184	$ 1	$ (4)	1,171	(13)	(16)	1,139	1,045
Beginning balance (in shares) at Mar. 31, 2018		98,274,669	(177,909)
Beginning balance at Mar. 31, 2018	2,294	$ 1	$ (4)	1,218	0	(27)	1,188	1,106
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase of shares for employee tax withholding, shares			(437)
Repurchase of shares for employee tax withholding	0						0
Stock-based compensation	1			1			1
Dividends declared	(41)			(8)	(33)		(41)
Distributions to noncontrolling interests	(11)						0	(11)
Net income (loss)	(2)				33		33	(35)
Other comprehensive loss, net of tax	(7)					(6)	(6)	(1)
Ending balance (in shares) at Jun. 30, 2018		98,274,669	(178,346)
Ending balance at Jun. 30, 2018	2,234	$ 1	$ (4)	1,211	0	(33)	1,175	1,059
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase of shares for employee tax withholding, shares			(437)
Repurchase of shares for employee tax withholding	0						0
Stock-based compensation	1			1			1
Dividends declared	(41)			(41)			(41)
Acquisitions	41						0	41
Sale of subsidiaries	(32)						0	(32)
Distributions to noncontrolling interests	(9)						0	(9)
Net income (loss)	(31)				(13)		(13)	(18)
Other comprehensive loss, net of tax	21					17	17	4
Ending balance (in shares) at Sep. 30, 2018		98,274,669	(178,783)
Ending balance at Sep. 30, 2018	2,184	$ 1	$ (4)	1,171	(13)	(16)	1,139	1,045
Beginning balance (in shares) at Dec. 31, 2018		98,274,669	(223,040)
Beginning balance at Dec. 31, 2018	2,159	$ 1	$ (5)	1,130	(27)	(52)	1,047	1,112
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Class A common stock under equity incentive award plan, shares		224,870
Issuance of Class A common stock under equity incentive award plan, net	0						0
Repurchase of shares for employee tax withholding, shares			(24,955)
Repurchase of shares for employee tax withholding	0						0
Stock-based compensation	1			1			1
Dividends declared	(41)			(41)			(41)
Contributions from noncontrolling interests	5						0	5
Distributions to noncontrolling interests	(11)						0	(11)
Net income (loss)	(46)				(30)		(30)	(16)
Other comprehensive loss, net of tax	(23)					(21)	(21)	(2)
Ending balance (in shares) at Mar. 31, 2019		98,499,539	(247,995)
Ending balance at Mar. 31, 2019	2,044	$ 1	$ (5)	1,090	(57)	(73)	956	1,088
Beginning balance (in shares) at Dec. 31, 2018		98,274,669	(223,040)
Beginning balance at Dec. 31, 2018	2,159	$ 1	$ (5)	1,130	(27)	(52)	1,047	1,112
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Contributions from noncontrolling interests	24				0
Distributions to noncontrolling interests	(33)				0
Net income (loss)	(147)
Other comprehensive loss, net of tax	(53)
Ending balance (in shares) at Sep. 30, 2019		98,489,599	(249,481)
Ending balance at Sep. 30, 2019	1,829	$ 1	$ (5)	1,009	(115)	(101)	789	1,040
Beginning balance (in shares) at Mar. 31, 2019		98,499,539	(247,995)
Beginning balance at Mar. 31, 2019	2,044	$ 1	$ (5)	1,090	(57)	(73)	956	1,088
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Forfeitures of Class A common stock under equity incentive award plan (in shares)		(9,343)
Forfeitures of Class A common stock under equity incentive award plan	0						0
Repurchase of shares for employee tax withholding, shares			(1,486)
Repurchase of shares for employee tax withholding	0						0
Stock-based compensation	1			1			1
Dividends declared	(41)			(41)			(41)
Distributions to noncontrolling interests	(10)						0	(10)
Net income (loss)	(30)				(7)		(7)	(23)
Other comprehensive loss, net of tax	(14)					(14)	(14)	0
Ending balance (in shares) at Jun. 30, 2019		98,490,196	(249,481)
Ending balance at Jun. 30, 2019	1,950	$ 1	$ (5)	1,050	(64)	(87)	895	1,055
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Forfeitures of Class A common stock under equity incentive award plan (in shares)		(597)
Forfeitures of Class A common stock under equity incentive award plan	0						0
Stock-based compensation	1			1			1
Dividends declared	(42)			(42)			(42)
Contributions from noncontrolling interests	19						0	19
Distributions to noncontrolling interests	(12)						0	(12)
Net income (loss)	(71)				(51)		(51)	(20)
Other comprehensive loss, net of tax	(16)					(14)	(14)	(2)
Ending balance (in shares) at Sep. 30, 2019		98,489,599	(249,481)
Ending balance at Sep. 30, 2019	$ 1,829	$ 1	$ (5)	$ 1,009	$ (115)	$ (101)	$ 789	$ 1,040