Schedule II. Condensed Financial Information of Registrant (Parent Company) (Schedule of Condensed Financial Information of Registrant, Statements of Operations and Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues
Net investment income									$ 1,817	$ 2,034	$ 1,988
Net realized investment gains (losses)									(52)	93	50
Total revenues	$ 2,403	$ 2,622	$ 2,574	$ 2,535	$ 2,448	$ 2,398	$ 2,366	$ 2,330	10,134	9,542	9,366
Expenses
Interest									138	161	159
Income tax expense									(151)	(411)	(278)
Net income	$ (84)	$ 336	$ 270	$ 291	$ 223	$ 144	$ 272	$ 260	813	899	859
Total comprehensive (loss) income									(81)	1,104	1,001
Parent Company
Revenues
Net investment income									10	6	3
Net realized investment gains (losses)									0	(42)	(7)
Total revenues									10	(36)	(4)
Expenses
Administrative and general									1	2	1
Interest									135	152	155
Total expenses									136	154	156
Loss from operations before income taxes and equity in net income of subsidiaries									(126)	(190)	(160)
Income tax expense									9	57	41
Loss before equity in net income of subsidiaries									(117)	(133)	(119)
Equity in net income of subsidiaries									930	1,032	978
Net income									813	899	859
Equity in other comprehensive income of subsidiaries									(894)	205	142
Total comprehensive (loss) income									$ (81)	$ 1,104	$ 1,001