Derivative Financial Instruments (Details) $ in Millions	9 Months Ended
	Sep. 30, 2015 USD ($) contract	Dec. 31, 2014 USD ($) contract
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Assumed recoveries under sale of credit protection	$ 0
Securities pledged in the form of margin deposits	11
Derivatives, Fair Value
Total asset derivatives, Notional amount	325	$ 407
Total liability derivatives, Notional amount	2,962	3,242
Total derivatives, Notional amount	$ 3,287	$ 3,649
Total asset derivatives, Number of contracts | contract	4,209	3,929
Total liability derivatives, Number of contracts | contract	5,239	3,331
Total derivatives, Number of contracts | contract	9,448	7,260
Total	$ 30	$ 92
Total	(300)	(354)
Total derivatives, Fair value, net	(270)	(262)
Asset derivatives, Gross asset	30	92
Asset derivatives, Gross liability	0	0
Liability derivatives, Gross asset	7	2
Liability derivatives, Gross liability	(307)	(356)
Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	307	322
Total liability derivatives, Notional amount	$ 2,906	$ 3,192
Total asset derivatives, Number of contracts | contract	4,209	3,929
Total liability derivatives, Number of contracts | contract	5,239	3,331
Total	$ 26	$ 89
Total	(307)	(353)
Asset derivatives, Gross asset	26	89
Asset derivatives, Gross liability	0	0
Liability derivatives, Gross asset	0	2
Liability derivatives, Gross liability	(307)	(355)
Foreign currency swap agreements | Derivatives designated as accounting hedging instruments | Other investments
Derivatives, Fair Value
Total asset derivatives, Notional amount	18	85
Total	4	3
Asset derivatives, Gross asset	4	3
Asset derivatives, Gross liability	0	0
Foreign currency swap agreements | Derivatives designated as accounting hedging instruments | Other liabilities & accrued expenses
Derivatives, Fair Value
Total liability derivatives, Notional amount	56	50
Total	7	(1)
Liability derivatives, Gross asset	7	0
Liability derivatives, Gross liability	0	(1)
Interest rate cap agreements | Derivatives not designated as accounting hedging instruments | Other investments
Derivatives, Fair Value
Total asset derivatives, Notional amount	135	163
Total	1	2
Asset derivatives, Gross asset	1	2
Asset derivatives, Gross liability	0	0
Interest rate cap agreements | Derivatives not designated as accounting hedging instruments | Other liabilities & accrued expenses
Derivatives, Fair Value
Total liability derivatives, Notional amount		11
Total		0
Liability derivatives, Gross asset		0
Liability derivatives, Gross liability		0
Financial Futures Contracts [Member] | Derivatives not designated as accounting hedging instruments | Other assets
Derivatives, Fair Value
Total asset derivatives, Notional amount	$ 0
Total asset derivatives, Number of contracts | contract	330
Total	$ 0
Asset derivatives, Gross asset	0
Asset derivatives, Gross liability	0
Financial Futures Contracts [Member] | Derivatives not designated as accounting hedging instruments | Other liabilities & accrued expenses
Derivatives, Fair Value
Total liability derivatives, Notional amount		$ 0
Total liability derivatives, Number of contracts | contract		200
Total		$ 0
Liability derivatives, Gross asset		0
Liability derivatives, Gross liability		0
Interest rate swap agreements | Derivatives not designated as accounting hedging instruments | Other liabilities & accrued expenses
Derivatives, Fair Value
Total liability derivatives, Notional amount	85	85
Total	0	1
Liability derivatives, Gross asset	0	1
Liability derivatives, Gross liability	0	0
Options | Derivatives not designated as accounting hedging instruments | Other investments
Derivatives, Fair Value
Total asset derivatives, Notional amount	$ 0	$ 0
Total asset derivatives, Number of contracts | contract	3,820	3,225
Total	$ 21	$ 83
Asset derivatives, Gross asset	21	83
Asset derivatives, Gross liability	0	0
Financial futures contracts | Derivatives not designated as accounting hedging instruments | Other assets
Derivatives, Fair Value
Total asset derivatives, Notional amount	$ 0	$ 0
Total asset derivatives, Number of contracts | contract	59	704
Total	$ 0	$ 1
Asset derivatives, Gross asset	0	1
Asset derivatives, Gross liability	0	0
Options and futures | Derivatives not designated as accounting hedging instruments | Other liabilities & accrued expenses
Derivatives, Fair Value
Total liability derivatives, Notional amount	$ 0	$ 0
Total liability derivatives, Number of contracts | contract	5,239	3,131
Total	$ (3)	$ (22)
Liability derivatives, Gross asset	0	0
Liability derivatives, Gross liability	(3)	(22)
Foreign currency forwards | Derivatives not designated as accounting hedging instruments | Other investments
Derivatives, Fair Value
Total asset derivatives, Notional amount	60	57
Total	0	0
Asset derivatives, Gross asset	0	0
Asset derivatives, Gross liability	0	0
Foreign currency forwards | Derivatives not designated as accounting hedging instruments | Other liabilities & accrued expenses
Derivatives, Fair Value
Total liability derivatives, Notional amount	10	36
Total	0	1
Liability derivatives, Gross asset	0	1
Liability derivatives, Gross liability	0	0
Guaranteed accumulation benefits | Derivatives not designated as accounting hedging instruments | Contractholder funds
Derivatives, Fair Value
Total liability derivatives, Notional amount	496	615
Total	(39)	(32)
Liability derivatives, Gross asset	0	0
Liability derivatives, Gross liability	(39)	(32)
Guaranteed withdrawal benefits | Derivatives not designated as accounting hedging instruments | Contractholder funds
Derivatives, Fair Value
Total liability derivatives, Notional amount	342	425
Total	(14)	(13)
Liability derivatives, Gross asset	0	0
Liability derivatives, Gross liability	(14)	(13)
Equity-indexed and forward starting options in life and annuity product contracts | Derivatives not designated as accounting hedging instruments | Contractholder funds
Derivatives, Fair Value
Total liability derivatives, Notional amount	1,773	1,786
Total	(242)	(278)
Liability derivatives, Gross asset	0	0
Liability derivatives, Gross liability	(242)	(278)
Other embedded derivative financial instruments | Derivatives not designated as accounting hedging instruments | Contractholder funds
Derivatives, Fair Value
Total liability derivatives, Notional amount	85	85
Total	0	0
Liability derivatives, Gross asset	0	0
Liability derivatives, Gross liability	0	0
Credit default swaps – buying protection | Derivatives not designated as accounting hedging instruments | Other investments
Derivatives, Fair Value
Total asset derivatives, Notional amount	29	19
Total	2	0
Asset derivatives, Gross asset	2	0
Asset derivatives, Gross liability	0	0
Credit default swaps – buying protection | Derivatives not designated as accounting hedging instruments | Other liabilities & accrued expenses
Derivatives, Fair Value
Total liability derivatives, Notional amount	15	49
Total	0	(1)
Liability derivatives, Gross asset	0	0
Liability derivatives, Gross liability	0	(1)
Credit default swaps – selling protection | Derivatives not designated as accounting hedging instruments | Other investments
Derivatives, Fair Value
Total asset derivatives, Notional amount	80	80
Total	1	2
Asset derivatives, Gross asset	1	2
Asset derivatives, Gross liability	0	0
Credit default swaps – selling protection | Derivatives not designated as accounting hedging instruments | Other liabilities & accrued expenses
Derivatives, Fair Value
Total liability derivatives, Notional amount	100	100
Total	(9)	(9)
Liability derivatives, Gross asset	0	0
Liability derivatives, Gross liability	(9)	(9)
Other contracts | Derivatives not designated as accounting hedging instruments | Other assets
Derivatives, Fair Value
Total asset derivatives, Notional amount	3	3
Total	1	1
Asset derivatives, Gross asset	1	1
Asset derivatives, Gross liability	$ 0	$ 0