Schedule II - Condensed Financial Information of Parent - Statements of Operations (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues:
Net investment income									$ 3,294	$ 3,354	$ 3,343
Net realized capital gains (losses)									(227)	(363)	(560)
Other revenue									371	342	385
Total revenues	$ 2,186	$ 2,184	$ 2,191	$ 2,057	$ 2,324	$ 2,110	$ 2,088	$ 2,266	8,618	8,788	8,716
Expenses:
Interest expense									184	288	197
Operating expenses									2,654	2,655	2,684
Total benefits and expenses	1,966	2,144	2,036	1,944	2,216	2,216	2,118	2,228	8,090	8,778	8,240
Income (loss) from continuing operations before income taxes	220	40	155	113	108	(106)	(30)	38	528	10	476
Income tax expense (benefit)									740	(29)	84
Net income (loss) before equity in earnings (losses) of subsidiaries									(2,792)	(298)	538
Equity in earnings (losses) of subsidiaries, net of tax									0	0	0
Net income (loss)	$ (3,083)	$ 214	$ 219	$ (142)	$ (375)	$ (251)	$ 137	$ 191	(2,792)	(298)	538
Parent Issuer
Revenues:
Net investment income									33	19	4
Net realized capital gains (losses)									0	1	(2)
Other revenue									8	1	3
Total revenues									41	21	5
Expenses:
Interest expense									155	238	150
Operating expenses									9	9	10
Total benefits and expenses									164	247	160
Income (loss) from continuing operations before income taxes									(123)	(226)	(155)
Income tax expense (benefit)									113	(90)	(52)
Net income (loss) before equity in earnings (losses) of subsidiaries									(236)	(136)	(103)
Equity in earnings (losses) of subsidiaries, net of tax									(2,756)	(191)	511
Net income (loss)									$ (2,992)	$ (327)	$ 408