Derivative Financial Instruments (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013 contract	Mar. 31, 2012	Dec. 31, 2012 contract
Derivative Financial Instruments
Assumed recoveries under sale of credit protection	$ 0	$ 0
Cash and securities pledged in the form of margin deposits	9
Derivatives, Fair Value
Total asset derivatives, Notional amount	6,037		7,961
Total liability derivatives, Notional amount	9,345		8,218
Total derivatives, Notional amount	15,382		16,179
Total asset derivatives, Number of contracts	13,402		13,489
Total liability derivatives, Number of contracts	12,825		12,619
Total derivatives, Number of contracts	26,227		26,108
Total asset derivatives, Fair value, net	225		158
Asset derivatives, Gross asset	249		182
Asset derivatives, Gross liability	(24)		(24)
Total liability derivatives, Fair value, net	(716)		(646)
Total derivatives, Fair value, net	(491)		(488)
Liability derivatives, Gross asset	26		23
Liability derivatives, Gross liability	(742)		(669)
Number of stock rights held by the company related to derivative contracts (in shares)	3,960		34,634
Number of stock warrants held by the company related to derivative contracts (in shares)	878,968		879,158
Derivatives designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	16		16
Total liability derivatives, Notional amount	132		135
Total asset derivatives, Fair value, net	3		2
Asset derivatives, Gross asset	3		2
Total liability derivatives, Fair value, net	(17)		(19)
Liability derivatives, Gross liability	(17)		(19)
Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	6,021		7,945
Total liability derivatives, Notional amount	9,213		8,083
Total asset derivatives, Number of contracts	13,402		13,489
Total liability derivatives, Number of contracts	12,825		12,619
Total asset derivatives, Fair value, net	222		156
Asset derivatives, Gross asset	246		180
Asset derivatives, Gross liability	(24)		(24)
Total liability derivatives, Fair value, net	(699)		(627)
Liability derivatives, Gross asset	26		23
Liability derivatives, Gross liability	(725)		(650)
Interest rate swap agreements | Other investments | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	4,284		5,541
Total asset derivatives, Fair value, net	18		19
Asset derivatives, Gross asset	26		28
Asset derivatives, Gross liability	(8)		(9)
Interest rate swap agreements | Other liabilities and accrued expenses | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total liability derivatives, Notional amount	2,185		1,185
Total liability derivatives, Fair value, net	20		16
Liability derivatives, Gross asset	22		18
Liability derivatives, Gross liability	(2)		(2)
Foreign currency swap agreements | Other investments | Derivatives designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	16		16
Total asset derivatives, Fair value, net	3		2
Asset derivatives, Gross asset	3		2
Foreign currency swap agreements | Other liabilities and accrued expenses | Derivatives designated as accounting hedging instruments
Derivatives, Fair Value
Total liability derivatives, Notional amount	132		135
Total liability derivatives, Fair value, net	(17)		(19)
Liability derivatives, Gross liability	(17)		(19)
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		250
Interest rate cap agreements | Other investments | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	159		372
Total asset derivatives, Fair value, net	1		1
Asset derivatives, Gross asset	1		1
Interest rate cap agreements | Other liabilities and accrued expenses | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total liability derivatives, Notional amount	380		429
Total liability derivatives, Fair value, net	2		1
Liability derivatives, Gross asset	2		1
Financial futures contracts - Interest rate contracts | Other assets | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Number of contracts	238		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			357
Options and warrants | Other investments | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	10		146
Total asset derivatives, Number of contracts	12,230		12,400
Total asset derivatives, Fair value, net	212		125
Asset derivatives, Gross asset	212		125
Options and warrants | Other liabilities and accrued expenses | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total liability derivatives, Notional amount	125
Total liability derivatives, Number of contracts	12,825		12,262
Total liability derivatives, Fair value, net	(125)		(58)
Liability derivatives, Gross asset	1
Liability derivatives, Gross liability	(126)		(58)
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	934		1,087
Total asset derivatives, Fair value, net	1		5
Asset derivatives, Gross asset	1		5
Foreign currency forwards and options | Other investments | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount			258
Total asset derivatives, Fair value, net			6
Asset derivatives, Gross asset			6
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
Total liability derivatives, Fair value, net			(1)
Liability derivatives, Gross asset			1
Liability derivatives, Gross liability			(2)
Foreign currency forwards | Other investments | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	191
Total asset derivatives, Fair value, net	(2)
Asset derivatives, Gross liability	(2)
Foreign currency forwards | Other liabilities and accrued expenses | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total liability derivatives, Notional amount	148
Total liability derivatives, Fair value, net	(2)
Liability derivatives, Gross asset	1
Liability derivatives, Gross liability	(3)
Conversion options | Fixed income securities | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	5		5
Equity-indexed call options | Fixed income securities | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount			90
Total asset derivatives, Fair value, net			9
Asset derivatives, Gross asset			9
Credit default swaps | Fixed income securities | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	12		12
Total asset derivatives, Fair value, net	(12)		(12)
Asset derivatives, Gross liability	(12)		(12)
Guaranteed accumulation benefits | Contractholder funds | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total liability derivatives, Notional amount	939		820
Total liability derivatives, Fair value, net	(70)		(86)
Liability derivatives, Gross liability	(70)		(86)
Guaranteed withdrawal benefits | Contractholder funds | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total liability derivatives, Notional amount	635		554
Total liability derivatives, Fair value, net	(30)		(39)
Liability derivatives, Gross liability	(30)		(39)
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	3,998		3,916
Total liability derivatives, Fair value, net	(459)		(419)
Liability derivatives, Gross liability	(459)		(419)
Other embedded derivative financial instruments | Other investments | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	1,000		1,000
Other embedded derivative financial instruments | Contractholder funds | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total liability derivatives, Notional amount	85		85
Total liability derivatives, Fair value, net	(8)		(9)
Liability derivatives, Gross liability	(8)		(9)
Credit Default Swaps - Buying Protection | Other investments | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	176		209
Asset derivatives, Gross asset	2		2
Asset derivatives, Gross liability	(2)		(2)
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	313		420
Total liability derivatives, Fair value, net	(3)		(3)
Liability derivatives, Gross asset			2
Liability derivatives, Gross liability	(3)		(5)
Credit Default Swaps - Selling Protection | Other investments | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	180		308
Total asset derivatives, Fair value, net	3		2
Asset derivatives, Gross asset	3		3
Asset derivatives, Gross liability			(1)
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	155		285
Total liability derivatives, Fair value, net	(24)		(29)
Liability derivatives, Gross asset			1
Liability derivatives, Gross liability	(24)		(30)
Other contracts | Other assets | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	4		4
Total asset derivatives, Fair value, net	1		1
Asset derivatives, Gross asset	$ 1		$ 1