Condensed Consolidated Statements of Equity (Unaudited) - USD ($) $ in Millions		Total	Common Stock [member]	Additional Paid-in Capital [member]	Retained Earnings [member]	Accumulated Other Comprehensive (Loss) Income [member]	Non-Controlling Interests [member]
Balance at Dec. 31, 2017		$ 5,962	$ 2	$ 3,825	$ 2,229	$ (45)	$ (49)
Balance (shares) at Dec. 31, 2017			215,000,000
Share-based compensation, net		3		3
Net income (loss)		149			150		(1)
Other comprehensive income (loss)		37				37
Dividends and dividend equivalents	[1]	(88)			(88)
Repurchase of common stock		(348)		(250)	(98)
Repurchases of common stock (Shares)			(14,000,000)
Balance at Mar. 31, 2018		5,715	$ 2	3,578	2,193	(8)	(50)
Balance (shares) at Mar. 31, 2018			201,000,000
Balance at Dec. 31, 2017		5,962	$ 2	3,825	2,229	(45)	(49)
Balance (shares) at Dec. 31, 2017			215,000,000
Net income (loss)		422
Other comprehensive income (loss)		36
Balance at Sep. 30, 2018		5,728	$ 2	3,585	2,196	(9)	(46)
Balance (shares) at Sep. 30, 2018			201,000,000
Balance at Mar. 31, 2018		5,715	$ 2	3,578	2,193	(8)	(50)
Balance (shares) at Mar. 31, 2018			201,000,000
Share-based compensation, net		3		3
Net income (loss)		218			216		2
Dividends and dividend equivalents	[1]	(178)			(178)
Distributions to noncontrolling interests		(1)					(1)
Balance at Jun. 30, 2018		5,757	$ 2	3,581	2,231	(8)	(49)
Balance (shares) at Jun. 30, 2018			201,000,000
Share-based compensation, net		4		4
Net income (loss)		55			52		3
Other comprehensive income (loss)		(1)				(1)
Dividends and dividend equivalents	[1]	(87)			(87)
Balance at Sep. 30, 2018		5,728	$ 2	3,585	2,196	(9)	(46)
Balance (shares) at Sep. 30, 2018			201,000,000
Balance at Dec. 31, 2018		$ 5,586	$ 2	3,589	2,047	(6)	(46)
Balance (shares) at Dec. 31, 2018		201,198,381	201,000,000
Share-based compensation, net		$ (1)		(1)
Net income (loss)		97			96		1
Dividends and dividend equivalents	[1]	(91)			(91)
Distributions to noncontrolling interests		(3)					(3)
Cumulative effect of change in accounting principle		(8)			(8)
Balance at Mar. 31, 2019		5,580	$ 2	3,588	2,044	(6)	(48)
Balance (shares) at Mar. 31, 2019			201,000,000
Balance at Dec. 31, 2018		$ 5,586	$ 2	3,589	2,047	(6)	(46)
Balance (shares) at Dec. 31, 2018		201,198,381	201,000,000
Net income (loss)		$ 190
Other comprehensive income (loss)		(2)
Balance at Sep. 30, 2019		$ 6,453	$ 2	4,572	1,931	(8)	(44)
Balance (shares) at Sep. 30, 2019		239,388,083	240,000,000
Balance at Mar. 31, 2019		$ 5,580	$ 2	3,588	2,044	(6)	(48)
Balance (shares) at Mar. 31, 2019			201,000,000
Share-based compensation, net		3		3
Share-based compensation, net (Shares)			1,000,000
Net income (loss)		84			82		2
Other comprehensive income (loss)		1				1
Dividends and dividend equivalents	[1]	(92)			(92)
Balance at Jun. 30, 2019		5,576	$ 2	3,591	2,034	(5)	(46)
Balance (shares) at Jun. 30, 2019			202,000,000
Issuance of common stock		978		978
Issuance of common stock (Shares)			38,000,000
Share-based compensation, net		3		3
Net income (loss)		9			5		4
Other comprehensive income (loss)		(3)				(3)
Dividends and dividend equivalents	[1]	(108)			(108)
Distributions to noncontrolling interests		(2)					(2)
Balance at Sep. 30, 2019		$ 6,453	$ 2	$ 4,572	$ 1,931	$ (8)	$ (44)
Balance (shares) at Sep. 30, 2019		239,388,083	240,000,000

[1] Dividends declared per common share were $0.45 for the three months ended March 31, 2019, June 30, 2019 and September 30, 2019. Dividends declared per common share were $0.43 for the three months ended March 31, 2018, June 30, 2018 and September 30, 2018. An additional special cash dividend of $0.45 per common share was declared for the three months ended June 30, 2018.