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)	Previously Reported	Previously Reported Common Stock	Previously Reported Additional Paid-In Capital	Previously Reported Accumulated Other Comprehensive Income (Loss)	Previously Reported Retained Earnings (Deficit)
Increase (Decrease) in Stockholders' Equity
Cumulative Effect of New Accounting Principle in Period of Adoption | Accounting Standards Update 2014-09	$ 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 at Dec. 31, 2017						$ 3,581	$ 3	$ 2,730	$ 818	$ 30
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
Beginning Balance at Dec. 31, 2018	3,322	3	2,728	108	483
Comprehensive income (loss):
Net income (loss)	65	0	0	0	65
Other comprehensive income (loss), after tax	502	0	0	502	0
Comprehensive income (loss)	567
Ending Balance at Mar. 31, 2019	3,889	3	2,728	747	$ 411
Increase (Decrease) in Stockholders' Equity
Cumulative Effect of New Accounting Principle in Period of Adoption | Accounting Standards Update 2018-02	$ 0	$ 0	$ 0	$ 137