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)	186	0	0	0	186
Other comprehensive income (loss), after tax	(546)	0	0	(546)	0
Comprehensive income (loss)	(360)
Dividends paid and distributions of capital	(126)	0	0	0	(126)
Employee related benefits	(1)	0	(1)	0	0
Ending Balance at Jun. 30, 2018	3,166	3	2,729	260	174
Beginning Balance at Mar. 31, 2018	3,372	3	2,730	438	201
Comprehensive income (loss):
Net income (loss)	99	0	0	0	99
Other comprehensive income (loss), after tax	(178)	0	0	(178)	0
Comprehensive income (loss)	(79)
Dividends paid and distributions of capital	(126)	0	0	0	(126)
Employee related benefits	(1)	0	(1)	0	0
Ending Balance at Jun. 30, 2018	3,166	3	2,729	260	174
Beginning Balance at Dec. 31, 2018	3,322	3	2,728	108	483
Comprehensive income (loss):
Net income (loss)	194	0	0	0	194
Other comprehensive income (loss), after tax	895	0	0	895	0
Comprehensive income (loss)	1,089
Dividends paid and distributions of capital	(396)	0	0	0	(396)
Employee related benefits	0	0	0	0	0
Ending Balance at Jun. 30, 2019	4,015	3	2,728	1,140	144
Increase (Decrease) in Stockholders' Equity
Cumulative Effect of New Accounting Principle in Period of Adoption | Accounting Standards Update 2018-02	0	0	0	0	0
Beginning Balance at Mar. 31, 2019	3,889	3	2,728	747	411
Comprehensive income (loss):
Net income (loss)	129	0	0	0	129
Other comprehensive income (loss), after tax	393	0	0	393	0
Comprehensive income (loss)	522
Dividends paid and distributions of capital	(396)	0	0	0	(396)
Employee related benefits	0	0	0	0	0
Ending Balance at Jun. 30, 2019	4,015	3	2,728	1,140	144
Increase (Decrease) in Stockholders' Equity
Cumulative Effect of New Accounting Principle in Period of Adoption | Accounting Standards Update 2018-02	$ 0	$ 0	$ 0	$ 137	$ (137)