Income Taxes - Components of Net Deferred Tax Assets (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Unrealized losses on credit derivative financial instruments, net	$ 20	$ 66
Unearned premium reserves, net	124	229
Loss and LAE reserve	0	216
Tax and loss bonds	0	50
Alternative minimum tax credit	59	17
Foreign tax credit	43	20
DAC	0	29
Investment basis difference	63	76
Deferred compensation	21	40
Net operating loss	38	64
FG VIE	13	14
Other	14	29
Total deferred income tax assets	395	850
Deferred tax liabilities:
Contingency reserves	0	82
Public debt	53	91
Unrealized appreciation on investments	91	84
Unrealized gains on CCS	13	22
Market discount	28	22
Loss and LAE reserve	27	0
DAC	12	0
Foreign BU	16	3
Other	14	30
Total deferred income tax liabilities	254	334
Less: Valuation allowance	43	19
Net deferred income tax asset	$ 98	$ 497