Derivative Financial Instruments (Details)	3 Months Ended
	Mar. 31, 2017 USD ($) contract	Dec. 31, 2016 USD ($) contract
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Assumed recoveries under sale of credit protection	$ 0
Securities pledged in the form of margin deposits	5,000,000
Derivatives, Fair Value
Total asset derivatives, Notional amount	359,000,000	$ 395,000,000
Total liability derivatives, Notional amount	2,527,000,000	2,524,000,000
Total derivatives, Notional amount	$ 2,886,000,000	$ 2,919,000,000
Total asset derivatives, Number of contracts | contract	4,070	3,923
Total liability derivatives, Number of contracts | contract	4,054	3,928
Total derivatives, Number of contracts | contract	8,124	7,851
Total asset derivatives	$ 102,000,000	$ 101,000,000
Total liability derivatives	(326,000,000)	(329,000,000)
Total derivatives, Fair value, net	(224,000,000)	(228,000,000)
Asset derivatives, Gross asset	105,000,000	103,000,000
Asset derivatives, Gross liability	(3,000,000)	(2,000,000)
Liability derivatives, Gross asset	4,000,000	0
Liability derivatives, Gross liability	(330,000,000)	(329,000,000)
Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	329,000,000	346,000,000
Total liability derivatives, Notional amount	$ 2,508,000,000	$ 2,524,000,000
Total asset derivatives, Number of contracts | contract	4,070	3,923
Total liability derivatives, Number of contracts | contract	4,054	3,928
Total asset derivatives	$ 101,000,000	$ 96,000,000
Total liability derivatives	(329,000,000)	(329,000,000)
Asset derivatives, Gross asset	104,000,000	98,000,000
Asset derivatives, Gross liability	(3,000,000)	(2,000,000)
Liability derivatives, Gross asset	1,000,000	0
Liability derivatives, Gross liability	(330,000,000)	(329,000,000)
Foreign currency swap agreements | Derivatives designated as accounting hedging instruments | Other investments
Derivatives, Fair Value
Total asset derivatives, Notional amount	30,000,000	49,000,000
Total asset derivatives	1,000,000	5,000,000
Asset derivatives, Gross asset	1,000,000	5,000,000
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	19,000,000
Total liability derivatives	3,000,000
Liability derivatives, Gross asset	3,000,000
Liability derivatives, Gross liability	0
Interest rate cap agreements | Derivatives not designated as accounting hedging instruments | Other investments
Derivatives, Fair Value
Total asset derivatives, Notional amount	33,000,000	65,000,000
Total asset derivatives	0	1,000,000
Asset derivatives, Gross asset	0	1,000,000
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	29,000,000
Total liability derivatives	1,000,000
Liability derivatives, Gross asset	1,000,000
Liability derivatives, Gross liability	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	4,041	3,917
Total asset derivatives	$ 100,000,000	$ 87,000,000
Asset derivatives, Gross asset	100,000,000	87,000,000
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	29	6
Total asset derivatives	$ 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 investments
Derivatives, Fair Value
Total asset derivatives, Notional amount	177,000,000	173,000,000
Total asset derivatives	1,000,000	7,000,000
Asset derivatives, Gross asset	3,000,000	8,000,000
Asset derivatives, Gross liability	(2,000,000)	(1,000,000)
Foreign currency forwards | Derivatives not designated as accounting hedging instruments | Other liabilities & accrued expenses
Derivatives, Fair Value
Total liability derivatives, Notional amount	1,000,000
Total liability derivatives	0
Liability derivatives, Gross asset	0
Liability derivatives, Gross liability	0
Credit default swaps – buying protection | Derivatives not designated as accounting hedging instruments | Other investments
Derivatives, Fair Value
Total asset derivatives, Notional amount	36,000,000	25,000,000
Total asset derivatives	(1,000,000)	(1,000,000)
Asset derivatives, Gross asset	0	0
Asset derivatives, Gross liability	(1,000,000)	(1,000,000)
Credit default swaps – buying protection | Derivatives not designated as accounting hedging instruments | Other liabilities & accrued expenses
Derivatives, Fair Value
Total liability derivatives, Notional amount	5,000,000	6,000,000
Total liability derivatives	0	0
Liability derivatives, Gross asset	0	0
Liability derivatives, Gross liability	0	0
Credit default swaps – selling protection | Derivatives not designated as accounting hedging instruments | Other investments
Derivatives, Fair Value
Total asset derivatives, Notional amount	80,000,000	80,000,000
Total asset derivatives	1,000,000	1,000,000
Asset derivatives, Gross asset	1,000,000	1,000,000
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	100,000,000	100,000,000
Total liability derivatives	(2,000,000)	(3,000,000)
Liability derivatives, Gross asset	0	0
Liability derivatives, Gross liability	(2,000,000)	(3,000,000)
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	4,054	3,928
Total liability derivatives	$ (43,000,000)	$ (37,000,000)
Liability derivatives, Gross asset	0	0
Liability derivatives, Gross liability	(43,000,000)	(37,000,000)
Other contracts | Derivatives not designated as accounting hedging instruments | Other assets
Derivatives, Fair Value
Total asset derivatives, Notional amount	3,000,000	3,000,000
Total asset derivatives	0	1,000,000
Asset derivatives, Gross asset	0	1,000,000
Asset 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	350,000,000	391,000,000
Total liability derivatives	(29,000,000)	(34,000,000)
Liability derivatives, Gross asset	0	0
Liability derivatives, Gross liability	(29,000,000)	(34,000,000)
Guaranteed withdrawal benefits | Derivatives not designated as accounting hedging instruments | Contractholder funds
Derivatives, Fair Value
Total liability derivatives, Notional amount	291,000,000	290,000,000
Total liability derivatives	(7,000,000)	(9,000,000)
Liability derivatives, Gross asset	0	0
Liability derivatives, Gross liability	(7,000,000)	(9,000,000)
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	1,732,000,000	1,737,000,000
Total liability derivatives	(249,000,000)	(246,000,000)
Liability derivatives, Gross asset	0	0
Liability derivatives, Gross liability	$ (249,000,000)	$ (246,000,000)