Consolidated Variable Interest Entities - Effect of Consolidating FG VIE's on Financial Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Variable Interest Entity [Line Items]
Net earned premiums	$ 145	$ 164
Net investment income	101	122
Fair value gains (losses) on FG VIEs	4	10
Loss and LAE	18	(59)
Income (loss) before income taxes	217	372
Less: tax provision (benefit)	20	55
Net income (loss)	197	317
Effect on OCI	(2)	0
Net cash flows provided by (used in) operating activities	27	102
Effect on shareholders' equity (decrease) increase	6,784		$ 6,839
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Net earned premiums	(3)	(4)
Net investment income	(1)	(1)
Fair value gains (losses) on FG VIEs	4	10
Loss and LAE	6	2
Income (loss) before income taxes	6	7
Less: tax provision (benefit)	1	3
Net income (loss)	5	4
Effect on OCI	(2)	0
Net cash flows provided by (used in) operating activities	2	$ 5
Effect on shareholders' equity (decrease) increase	$ 5		$ 2