Other Comprehensive Income - Changes in AOCI by Component (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Balance at beginning of period				$ 160				$ 515	$ 160	$ 515	$ 368
Other comprehensive income (loss) before reclassifications									169	(341)
Amounts reclassified from AOCI to:
Net realized investment gains (losses)	(35)	(19)	(8)	2	29	(7)	2	28	(60)	52	1
Interest expense	(25)	(27)	(20)	(20)	(19)	(21)	(21)	(21)	(92)	(82)	(92)
Total (provision) benefit for income taxes	(224)	(133)	(59)	(27)	(140)	(152)	(110)	68	(443)	(334)	(22)
Less: reclassification adjustment for gains (losses) included in net income (loss), net of tax provision (benefit) of $(21), $5 and $(7)									41	(14)	4
Other comprehensive income (loss)									210	(355)	147
Net current period other comprehensive income (loss)									210	(355)
Balance at end of period	370				160				370	160	515
Reclassification out of Accumulated Other Comprehensive Income [Member]
Amounts reclassified from AOCI to:
Net realized investment gains (losses)									62	(19)
Interest expense									0	(1)
Total before tax									62	(20)
Total (provision) benefit for income taxes									(21)	6
Less: reclassification adjustment for gains (losses) included in net income (loss), net of tax provision (benefit) of $(21), $5 and $(7)									41	(14)
Net Unrealized Gains (Losses) on Investments with no Other-Than-Temporary Impairment [Member]
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Balance at beginning of period				178				517	178	517	365
Other comprehensive income (loss) before reclassifications									196	(309)
Amounts reclassified from AOCI to:
Other comprehensive income (loss)											152
Net current period other comprehensive income (loss)									189	(339)
Balance at end of period	367				178				367	178	517
Net Unrealized Gains (Losses) on Investments with no Other-Than-Temporary Impairment [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Amounts reclassified from AOCI to:
Net realized investment gains (losses)									(12)	(43)
Interest expense									0	0
Total before tax									(12)	(43)
Total (provision) benefit for income taxes									5	13
Less: reclassification adjustment for gains (losses) included in net income (loss), net of tax provision (benefit) of $(21), $5 and $(7)									(7)	(30)
Net Unrealized Gains (Losses) on Investments with Other-Than-Temporary Impairment [Member]
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Balance at beginning of period				(24)				(5)	(24)	(5)	2
Other comprehensive income (loss) before reclassifications									(20)	(35)
Amounts reclassified from AOCI to:
Other comprehensive income (loss)											(7)
Net current period other comprehensive income (loss)									28	(19)
Balance at end of period	4				(24)				4	(24)	(5)
Net Unrealized Gains (Losses) on Investments with Other-Than-Temporary Impairment [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Amounts reclassified from AOCI to:
Net realized investment gains (losses)									74	24
Interest expense									0	0
Total before tax									74	24
Total (provision) benefit for income taxes									(26)	(8)
Less: reclassification adjustment for gains (losses) included in net income (loss), net of tax provision (benefit) of $(21), $5 and $(7)									48	16
Accumulated Translation Adjustment [Member]
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Balance at beginning of period				(3)				(6)	(3)	(6)	(8)
Other comprehensive income (loss) before reclassifications									(7)	3
Amounts reclassified from AOCI to:
Other comprehensive income (loss)											2
Net current period other comprehensive income (loss)									(7)	3
Balance at end of period	(10)				(3)				(10)	(3)	(6)
Accumulated Translation Adjustment [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Amounts reclassified from AOCI to:
Net realized investment gains (losses)									0	0
Interest expense									0	0
Total before tax									0	0
Total (provision) benefit for income taxes									0	0
Less: reclassification adjustment for gains (losses) included in net income (loss), net of tax provision (benefit) of $(21), $5 and $(7)									0	0
Cash Flow Hedge [Member]
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Balance at beginning of period				9				9	9	9	9
Other comprehensive income (loss) before reclassifications									0	0
Amounts reclassified from AOCI to:
Other comprehensive income (loss)											0
Net current period other comprehensive income (loss)									0	0
Balance at end of period	9				9				9	9	9
Cash Flow Hedge [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Amounts reclassified from AOCI to:
Net realized investment gains (losses)									0	0
Interest expense									0	(1)
Total before tax									0	(1)
Total (provision) benefit for income taxes									0	1
Less: reclassification adjustment for gains (losses) included in net income (loss), net of tax provision (benefit) of $(21), $5 and $(7)									$ 0	$ 0