Derivative Financial Instruments (Details) (USD $) In Millions, except Share data, unless otherwise specified	6 Months Ended
	Jun. 30, 2013 contract	Jun. 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	17
Derivatives, Fair Value
Total asset derivatives, Notional amount	3,105		7,961
Total liability derivatives, Notional amount	6,547		8,218
Total derivatives, Notional amount	9,652		16,179
Total asset derivatives, Number of contracts	11,110		13,489
Total liability derivatives, Number of contracts	12,123		12,619
Total derivatives, Number of contracts	23,233		26,108
Total asset derivatives, Fair value, net	194		158
Asset derivatives, Gross asset	213		182
Asset derivatives, Gross liability	(19)		(24)
Total liability derivatives, Fair value, net	(671)		(646)
Total derivatives, Fair value, net	(477)		(488)
Liability derivatives, Gross asset	7		23
Liability derivatives, Gross liability	(678)		(669)
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)	849,107		879,158
Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	3,016		7,945
Total liability derivatives, Notional amount	6,488		8,083
Total asset derivatives, Number of contracts	11,110		13,489
Total liability derivatives, Number of contracts	12,123		12,619
Total asset derivatives, Fair value, net	195		156
Asset derivatives, Gross asset	210		180
Asset derivatives, Gross liability	(15)		(24)
Total liability derivatives, Fair value, net	(666)		(627)
Liability derivatives, Gross asset	7		23
Liability derivatives, Gross liability	(673)		(650)
Interest rate swap agreements | Other investments | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	1,332		5,541
Total asset derivatives, Fair value, net	6		19
Asset derivatives, Gross asset	7		28
Asset derivatives, Gross liability	(1)		(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	85		1,185
Total liability derivatives, Fair value, net	5		16
Liability derivatives, Gross asset	5		18
Liability derivatives, Gross liability			(2)
Foreign currency swap agreements | Other investments | Derivatives designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	89		16
Total asset derivatives, Fair value, net	(1)		2
Asset derivatives, Gross asset	3		2
Asset derivatives, Gross liability	(4)
Foreign currency swap agreements | Other liabilities and accrued expenses | Derivatives designated as accounting hedging instruments
Derivatives, Fair Value
Total liability derivatives, Notional amount	59		135
Total liability derivatives, Fair value, net	(5)		(19)
Liability derivatives, Gross liability	(5)		(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
Interest rate cap agreements | Other investments | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	290		372
Total asset derivatives, Fair value, net	5		1
Asset derivatives, Gross asset	5		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	149		429
Total liability derivatives, Fair value, net			1
Liability derivatives, Gross asset			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			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	13		146
Total asset derivatives, Number of contracts	11,110		12,400
Total asset derivatives, Fair value, net	192		125
Asset derivatives, Gross asset	192		125
Options and warrants | Other liabilities and accrued expenses | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total liability derivatives, Notional amount	108
Total liability derivatives, Number of contracts	12,123		12,262
Total liability derivatives, Fair value, net	(116)		(58)
Liability derivatives, Gross liability	(116)		(58)
Financial futures contracts - Equity and index contracts | Other assets | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Fair value, net	2		5
Asset derivatives, Gross asset	2		5
Foreign currency forwards | Other investments | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	45
Foreign currency forwards | Other liabilities and accrued expenses | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total liability derivatives, Notional amount	304
Total liability derivatives, Fair value, net	(6)
Liability derivatives, Gross asset	2
Liability derivatives, Gross liability	(8)
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)
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	786		820
Total liability derivatives, Fair value, net	(59)		(86)
Liability derivatives, Gross liability	(59)		(86)
Guaranteed withdrawal benefits | Contractholder funds | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total liability derivatives, Notional amount	539		554
Total liability derivatives, Fair value, net	(24)		(39)
Liability derivatives, Gross liability	(24)		(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	3,996		3,916
Total liability derivatives, Fair value, net	(445)		(419)
Liability derivatives, Gross liability	(445)		(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	(5)		(9)
Liability derivatives, Gross liability	(5)		(9)
Credit Default Swaps - Buying Protection | Other investments | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Notional amount	175		209
Asset derivatives, Gross asset	1		2
Asset derivatives, Gross liability	(1)		(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	291		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	140		308
Total asset derivatives, Fair value, net	1		2
Asset derivatives, Gross asset	2		3
Asset derivatives, Gross liability	(1)		(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	145		285
Total liability derivatives, Fair value, net	(13)		(29)
Liability derivatives, Gross asset			1
Liability derivatives, Gross liability	(13)		(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
Options, futures and warrants | Other assets | Derivatives not designated as accounting hedging instruments
Derivatives, Fair Value
Total asset derivatives, Number of contracts			1,087