Shareholder's Equity (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' Equity Attributable to Parent Period Begin		$ 3,288		$ 3,288
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	$ 9		$ (32)	18	$ (46)
Dividends, Preferred Stock, Cash	3		0	5	0
Transfers (To) From Parent	0		151	(161)	362
Stockholders' Equity Attributable to Parent Period End	$ 3,317			3,317
Preferred Stock, Dividends Per Share, Declared	$ 20.00	$ 20.00
Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' Equity Attributable to Parent Period Begin		$ 2		2	0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent				0	0
Dividends, Preferred Stock, Cash				0
Proceeds from Issuance of Shares under Incentive and Share-based Compensation Plans, Including Stock Options				0
Transfers (To) From Parent					0
Stockholders' Equity Attributable to Parent Period End	$ 2		0	2	0
Additional Paid-in Capital [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' Equity Attributable to Parent Period Begin		3,812		3,812	0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent				0	0
Dividends, Preferred Stock, Cash				0
Proceeds from Issuance of Shares under Incentive and Share-based Compensation Plans, Including Stock Options				16
Transfers (To) From Parent					0
Stockholders' Equity Attributable to Parent Period End	3,828		0	3,828	0
Retained Earnings [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' Equity Attributable to Parent Period Begin		0		0	0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent				(10)	0
Dividends, Preferred Stock, Cash				(5)
Proceeds from Issuance of Shares under Incentive and Share-based Compensation Plans, Including Stock Options				0
Transfers (To) From Parent					0
Stockholders' Equity Attributable to Parent Period End	(15)		0	(15)	0
AOCI Attributable to Parent [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' Equity Attributable to Parent Period Begin		(526)		(526)	(181)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent				28	(13)
Dividends, Preferred Stock, Cash				0
Proceeds from Issuance of Shares under Incentive and Share-based Compensation Plans, Including Stock Options				0
Transfers (To) From Parent					0
Stockholders' Equity Attributable to Parent Period End	(498)		(194)	(498)	(194)
Former parent investment [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' Equity Attributable to Parent Period Begin		0		0	5,343
Comprehensive Income (Loss), Net of Tax, Attributable to Parent				0	(33)
Dividends, Preferred Stock, Cash				0
Proceeds from Issuance of Shares under Incentive and Share-based Compensation Plans, Including Stock Options				0
Transfers (To) From Parent					390
Stockholders' Equity Attributable to Parent Period End	0		5,700	0	5,700
Parent [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' Equity Attributable to Parent Period Begin		$ 3,288		3,288	5,162
Comprehensive Income (Loss), Net of Tax, Attributable to Parent				18	(46)
Dividends, Preferred Stock, Cash				(5)
Proceeds from Issuance of Shares under Incentive and Share-based Compensation Plans, Including Stock Options				16
Transfers (To) From Parent					390
Stockholders' Equity Attributable to Parent Period End	$ 3,317		$ 5,506	$ 3,317	$ 5,506