Consolidated Statements of Equity - USD ($) $ in Millions	Total	Common Stock [member]	Additional Paid-in Capital [member]	Retained Earnings [member]	Accumulated Other Comprehensive Loss [member]	Net Parent Investment [Member]	Non-Controlling Interests [member]
Balance at Dec. 31, 2014	$ 2,593				$ (51)	$ 2,668	$ (24)
Net income	299					292	7
Other comprehensive income (loss)	(12)				(12)
Net transfers (to) from Parent	3					3
Capital contribution from Parent	2					2
Cash dividends paid to Parent	(81)					(81)
Distributions to noncontrolling interests	(7)						(7)
Balance at Dec. 31, 2015	2,797				(63)	2,884	(24)
Net income	139					133	6
Other comprehensive income (loss)	(7)				(7)
Net transfers (to) from Parent	40					40
Capital contribution from Parent	337					337
Cash contribution from Parent	987					987
Distribution to Parent	(256)				3	(259)
Cash dividends paid to Parent	(180)					(180)
Distributions to noncontrolling interests	(32)						(32)
Cumulative effect of the adoptionof ASU 2015-02	(2)					(3)	1
Balance at Dec. 31, 2016	3,823				(67)	3,939	(49)
Net income	2,631			$ 2,625			6
Other comprehensive income (loss)	22				22
Net transfers (to) from Parent	(13)					(13)
Issuance of common stock and reclassification of former Parent investment		$ 2	$ 3,924			(3,926)
Issuance of common stock and reclassification of former Parent investment (shares)		198,000,000
Share-based compensation	11		11
Share-based compensation (Shares)		1,000,000
Dividends and dividend equivalents	(506)		(110)	(396)
Dividends and dividend equivalents (Shares)		16,000,000
Distributions to noncontrolling interests	(6)						(6)
Balance at Dec. 31, 2017	$ 5,962	$ 2	$ 3,825	$ 2,229	$ (45)	$ 0	$ (49)
Balance (shares) at Dec. 31, 2017	214,845,244	215,000,000