Condensed Consolidated Statements of Changes in Shareholder's Equity - USD ($) $ in Millions	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings (Deficit)
Beginning Balance at Dec. 31, 2016	$ 3,377	$ 3	$ 2,994	$ 560	$ (180)
Comprehensive income (loss):
Net income (loss)	54	0	0	0	54
Other comprehensive income (loss), after tax	53	0	0	53	0
Comprehensive income (loss)	107
Ending Balance at Mar. 31, 2017	3,484	3	2,994	613	(126)
Increase (Decrease) in Stockholders' Equity
Cumulative Effect of New Accounting Principle in Period of Adoption | Accounting Standards Update 2014-09 [Member]	72	0	0	0	72
Cumulative Effect of New Accounting Principle in Period of Adoption | Accounting Standards Update 2016-01	0	0	0	(12)	12
Beginning Balance (Scenario, Previously Reported [Member]) at Dec. 31, 2017	3,581	3	2,730	818	30
Beginning Balance at Dec. 31, 2017	3,581
Balance as adjusted at Dec. 31, 2017	3,653	3	2,730	806	114
Comprehensive income (loss):
Net income (loss)	87	0	0	0	87
Other comprehensive income (loss), after tax	(368)	0	0	(368)	0
Comprehensive income (loss)	(281)
Ending Balance at Mar. 31, 2018	$ 3,372	$ 3	$ 2,730	$ 438	$ 201