Derivative Financial Instruments (Details) (USD $)	9 Months Ended
	Sep. 30, 2013 contract	Sep. 30, 2012	Dec. 31, 2012 contract
Derivative Financial Instruments
Assumed recoveries under sale of credit protection	$ 0	$ 0
Securities pledged in the form of margin deposits	15,000,000
Derivatives, Fair Value
Total asset derivatives, Notional amount	2,472,000,000		7,961,000,000
Total liability derivatives, Notional amount	6,907,000,000		8,218,000,000
Total derivatives, Notional amount	9,379,000,000		16,179,000,000
Total asset derivatives, Number of contracts	10,570		13,489
Total liability derivatives, Number of contracts	12,123		12,619
Total derivatives, Number of contracts	22,693		26,108
Derivative assets net amount on balance sheet	216,000,000		158,000,000
Asset derivatives, Gross asset	232,000,000		182,000,000
Asset derivatives, Gross liability	(16,000,000)		(24,000,000)
Total liability derivatives, Fair value, net	(685,000,000)		(646,000,000)
Total derivatives, Fair value, net	(469,000,000)		(488,000,000)
Liability derivatives, Gross asset	12,000,000		23,000,000
Liability derivatives, Gross liability	(697,000,000)		(669,000,000)
Number of stock rights held by the company related to derivative contracts (in shares)	2,860		34,634
Number of stock warrants held by the company related to derivative contracts (in shares)	887,964		879,158
Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	2,456,000,000		7,945,000,000
Total liability derivatives, Notional amount	6,775,000,000		8,083,000,000
Total asset derivatives, Number of contracts	10,570		13,489
Total liability derivatives, Number of contracts	12,123		12,619
Derivative assets net amount on balance sheet	214,000,000		156,000,000
Asset derivatives, Gross asset	230,000,000		180,000,000
Asset derivatives, Gross liability	(16,000,000)		(24,000,000)
Total liability derivatives, Fair value, net	(669,000,000)		(627,000,000)
Liability derivatives, Gross asset	12,000,000		23,000,000
Liability derivatives, Gross liability	(681,000,000)		(650,000,000)
Interest rate swap agreements | Other investments | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	700,000,000		5,541,000,000
Derivative assets net amount on balance sheet	3,000,000		19,000,000
Asset derivatives, Gross asset	4,000,000		28,000,000
Asset derivatives, Gross liability	(1,000,000)		(9,000,000)
Interest rate swap agreements | Other liabilities and accrued expenses | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total liability derivatives, Notional amount	685,000,000		1,185,000,000
Total liability derivatives, Fair value, net	8,000,000		16,000,000
Liability derivatives, Gross asset	8,000,000		18,000,000
Liability derivatives, Gross liability			(2,000,000)
Foreign currency swap agreements | Other investments | Derivatives designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	16,000,000		16,000,000
Derivative assets net amount on balance sheet	2,000,000		2,000,000
Asset derivatives, Gross asset	2,000,000		2,000,000
Foreign currency swap agreements | Other liabilities and accrued expenses | Derivatives designated as accounting hedging instruments
Derivatives, Fair Value
Total liability derivatives, Notional amount	132,000,000		135,000,000
Total liability derivatives, Fair value, net	(16,000,000)		(19,000,000)
Liability derivatives, Gross liability	(16,000,000)		(19,000,000)
Interest rate swaption agreements | Other liabilities and accrued expenses | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total liability derivatives, Notional amount			250,000,000
Interest rate cap agreements | Other investments | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	122,000,000		372,000,000
Derivative assets net amount on balance sheet	2,000,000		1,000,000
Asset derivatives, Gross asset	2,000,000		1,000,000
Interest rate cap agreements | Other liabilities and accrued expenses | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total liability derivatives, Notional amount	234,000,000		429,000,000
Total liability derivatives, Fair value, net	3,000,000		1,000,000
Liability derivatives, Gross asset	3,000,000		1,000,000
Financial futures contracts - Interest rate contracts | Other assets | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Number of contracts			2
Financial futures contracts - Interest rate contracts | Other liabilities and accrued expenses | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total liability derivatives, Number of contracts	400		357
Options and warrants | Other investments | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	3,000,000		146,000,000
Total asset derivatives, Number of contracts	10,570		12,400
Derivative assets net amount on balance sheet	208,000,000		125,000,000
Asset derivatives, Gross asset	208,000,000		125,000,000
Options and futures | Other liabilities and accrued expenses | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total liability derivatives, Notional amount	81,000,000
Total liability derivatives, Number of contracts	11,723		12,262
Total liability derivatives, Fair value, net	(126,000,000)		(58,000,000)
Liability derivatives, Gross asset	1,000,000
Liability derivatives, Gross liability	(127,000,000)		(58,000,000)
Financial futures contracts - Equity and index contracts | Other assets | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Number of contracts			1,087
Derivative assets net amount on balance sheet			5,000,000
Asset derivatives, Gross asset			5,000,000
Foreign currency forwards and options | Other investments | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	355,000,000		258,000,000
Derivative assets net amount on balance sheet	11,000,000		6,000,000
Asset derivatives, Gross asset	12,000,000		6,000,000
Asset derivatives, Gross liability	(1,000,000)
Foreign currency forwards and options | Other liabilities and accrued expenses | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total liability derivatives, Notional amount			139,000,000
Total liability derivatives, Fair value, net			(1,000,000)
Liability derivatives, Gross asset			1,000,000
Liability derivatives, Gross liability			(2,000,000)
Conversion options | Fixed income securities | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	5,000,000		5,000,000
Equity-indexed call options | Fixed income securities | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount			90,000,000
Derivative assets net amount on balance sheet			9,000,000
Asset derivatives, Gross asset			9,000,000
Credit default swaps | Fixed income securities | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	12,000,000		12,000,000
Derivative assets net amount on balance sheet	(12,000,000)		(12,000,000)
Asset derivatives, Gross liability	(12,000,000)		(12,000,000)
Guaranteed accumulation benefits | Contractholder funds | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total liability derivatives, Notional amount	734,000,000		820,000,000
Total liability derivatives, Fair value, net	(54,000,000)		(86,000,000)
Liability derivatives, Gross liability	(54,000,000)		(86,000,000)
Guaranteed withdrawal benefits | Contractholder funds | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total liability derivatives, Notional amount	505,000,000		554,000,000
Total liability derivatives, Fair value, net	(19,000,000)		(39,000,000)
Liability derivatives, Gross liability	(19,000,000)		(39,000,000)
Equity-indexed and forward starting options in life and annuity product contracts | Contractholder funds | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total liability derivatives, Notional amount	1,463,000,000		3,916,000,000
Total liability derivatives, Fair value, net	(205,000,000)		(419,000,000)
Liability derivatives, Gross liability	(205,000,000)		(419,000,000)
Equity-indexed and forward starting options in life and annuity product contracts | Liabilities held for sale | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total liability derivatives, Notional amount	2,493,000,000
Total liability derivatives, Fair value, net	(249,000,000)
Liability derivatives, Gross liability	(249,000,000)
Other embedded derivative financial instruments | Other investments | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	1,000,000,000		1,000,000,000
Other embedded derivative financial instruments | Contractholder funds | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total liability derivatives, Notional amount	85,000,000		85,000,000
Total liability derivatives, Fair value, net	(5,000,000)		(9,000,000)
Liability derivatives, Gross liability	(5,000,000)		(9,000,000)
Credit Default Swaps - Buying Protection | Other investments | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	101,000,000		209,000,000
Derivative assets net amount on balance sheet	(1,000,000)
Asset derivatives, Gross asset	1,000,000		2,000,000
Asset derivatives, Gross liability	(2,000,000)		(2,000,000)
Credit Default Swaps - Buying Protection | Other liabilities and accrued expenses | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total liability derivatives, Notional amount	355,000,000		420,000,000
Total liability derivatives, Fair value, net	(7,000,000)		(3,000,000)
Liability derivatives, Gross asset			2,000,000
Liability derivatives, Gross liability	(7,000,000)		(5,000,000)
Credit Default Swaps - Selling Protection | Other investments | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	155,000,000		308,000,000
Derivative assets net amount on balance sheet	2,000,000		2,000,000
Asset derivatives, Gross asset	2,000,000		3,000,000
Asset derivatives, Gross liability			(1,000,000)
Credit Default Swaps - Selling Protection | Other liabilities and accrued expenses | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total liability derivatives, Notional amount	140,000,000		285,000,000
Total liability derivatives, Fair value, net	(15,000,000)		(29,000,000)
Liability derivatives, Gross asset			1,000,000
Liability derivatives, Gross liability	(15,000,000)		(30,000,000)
Other contracts | Other assets | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	3,000,000		4,000,000
Derivative assets net amount on balance sheet	1,000,000		1,000,000
Asset derivatives, Gross asset	$ 1,000,000		$ 1,000,000