Condensed Consolidated Statements of Changes in Shareholder's Equity - USD ($)	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings (Deficit)
Beginning Balance at Dec. 31, 2018	$ 3,435,000,000	$ 3,000,000	$ 2,816,000,000	$ 108,000,000	$ 508,000,000
Comprehensive income (loss):
Net income (loss)	160,000,000				160,000,000
Other comprehensive income (loss), after tax	895,000,000			895,000,000
Comprehensive income (loss)	1,055,000,000
Ending Balance at Jun. 30, 2019	$ 4,094,000,000	$ 3,000,000	$ 2,816,000,000	$ 1,140,000,000	$ 135,000,000
Comprehensive income (loss):
New Accounting Pronouncement or Change in Accounting Principle, Description | Accounting Standards Update 2018-02	—	—	—	137	(137)
Dividends	$ (396,000,000)				$ (396,000,000)
Beginning Balance at Mar. 31, 2019	3,982,000,000	$ 3,000,000	$ 2,816,000,000	$ 747,000,000	416,000,000
Comprehensive income (loss):
Net income (loss)	115,000,000	0	0	0	115,000,000
Other comprehensive income (loss), after tax	393,000,000	0	0	393,000,000	0
Comprehensive income (loss)	508,000,000
Ending Balance at Jun. 30, 2019	4,094,000,000	3,000,000	2,816,000,000	1,140,000,000	135,000,000
Comprehensive income (loss):
Dividends	(396,000,000)				(396,000,000)
Beginning Balance at Dec. 31, 2019	4,443,000,000	3,000,000	2,873,000,000	1,292,000,000	275,000,000
Comprehensive income (loss):
Net income (loss)	127,000,000	0	0	0	127,000,000
Other comprehensive income (loss), after tax	243,000,000	0	0	243,000,000
Comprehensive income (loss)	370,000,000
Ending Balance at Jun. 30, 2020	$ 4,511,000,000	$ 3,000,000	$ 2,873,000,000	$ 1,535,000,000	$ 100,000,000
Comprehensive income (loss):
New Accounting Pronouncement or Change in Accounting Principle, Description | Accounting Standards Update 2016-13	(8)	—	—	—	(8)
Dividends	$ (294,000,000)	$ 0	$ 0	$ 0	$ (294,000,000)
Beginning Balance at Mar. 31, 2020	3,710,000,000	3,000,000	2,873,000,000	533,000,000	301,000,000
Comprehensive income (loss):
Net income (loss)	93,000,000	0	0	0	93,000,000
Other comprehensive income (loss), after tax	1,002,000,000	0	0	1,002,000,000	0
Comprehensive income (loss)	1,095,000,000
Ending Balance at Jun. 30, 2020	$ 4,511,000,000	$ 3,000,000	$ 2,873,000,000	$ 1,535,000,000	$ 100,000,000
Comprehensive income (loss):
New Accounting Pronouncement or Change in Accounting Principle, Description | Accounting Standards Update 2016-13	—				—
Dividends	$ (294,000,000)				$ (294,000,000)