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, 2018	$ 3,435	$ 3	$ 2,816	$ 108	$ 508
Comprehensive income (loss):
Net income (loss)	45	0	0	0	45
Other comprehensive income (loss), after tax	502	0	0	502	0
Comprehensive income (loss)	547
Ending Balance at Mar. 31, 2019	3,982	3	2,816	747	416
Beginning Balance at Dec. 31, 2018	3,435	3	2,816	108	508
Comprehensive income (loss):
Net income (loss)	45
Ending Balance at Dec. 31, 2019	4,443	3	2,873	1,292	275
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)
Comprehensive income (loss):
Net income (loss)	34	0	0	0	34
Other comprehensive income (loss), after tax	(759)	0	0	(759)	0
Comprehensive income (loss)	(725)
Ending Balance at Mar. 31, 2020	3,710	3	2,873	533	301
Increase (Decrease) in Stockholders' Equity
Cumulative Effect of New Accounting Principle in Period of Adoption | Accounting Standards Update 2016-13	$ (8)	$ 0	$ 0	$ 0	$ (8)