Derivative Instruments (Details) - Gross amounts of derivative fair values contained in the consolidated balance sheet (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012		Dec. 31, 2011
Designated as Hedging Instrument [Member]
Derivatives Fair Value [Line Items]
Asset derivative notional amount	$ 2,088,759		$ 2,189,699
Asset derivative fair value	174,196	[1]	135,148	[1]
Liability derivative notional amount	724,842		457,892
Liability derivative fair value	(5,883)	[1]	(4,518)	[1]
Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivatives Fair Value [Line Items]
Asset derivative notional amount	156,254	[2]	156,271	[2]
Asset derivative fair value	116,881	[1],[2]	109,761	[1],[2]
Liability derivative notional amount	0	[2]	0	[2]
Liability derivative fair value	0	[1],[2]	0	[1],[2]
Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member]
Derivatives Fair Value [Line Items]
Asset derivative notional amount	1,932,505		2,033,428
Asset derivative fair value	57,315	[1]	25,387	[1]
Liability derivative notional amount	724,842		457,892
Liability derivative fair value	(5,883)	[1]	(4,518)	[1]
Not Designated as Hedging Instrument [Member]
Derivatives Fair Value [Line Items]
Asset derivative notional amount	296,782		576,974
Asset derivative fair value	4,826	[1]	11,591	[1]
Liability derivative notional amount	610,817		1,063,914
Liability derivative fair value	(41,559)	[1]	(58,544)	[1]
Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Investment Related Derivatives [Member]
Derivatives Fair Value [Line Items]
Asset derivative notional amount	60,802		70,978
Asset derivative fair value	2,229	[1]	1,946	[1]
Liability derivative notional amount	32,642		55,033
Liability derivative fair value	(163)	[1]	(43)	[1]
Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Investment Related Derivatives [Member]
Derivatives Fair Value [Line Items]
Asset derivative notional amount	27,223		232,422
Asset derivative fair value	255	[1]	3,759	[1]
Liability derivative notional amount	59,666		384,592
Liability derivative fair value	(754)	[1]	(11,737)	[1]
Not Designated as Hedging Instrument [Member] | Credit Exposure [Member] | Investment Related Derivatives [Member]
Derivatives Fair Value [Line Items]
Asset derivative notional amount	91,250		172,500
Asset derivative fair value	1,624	[1]	5,271	[1]
Liability derivative notional amount	374,013		449,513
Liability derivative fair value	(15,015)	[1]	(13,986)	[1]
Not Designated as Hedging Instrument [Member] | Credit Exposure [Member] | Financial Operations Derivatives [Member]
Derivatives Fair Value [Line Items]
Asset derivative notional amount	0	[2],[3]	0	[2],[3]
Asset derivative fair value	0	[1],[2],[3]	0	[1],[2],[3]
Liability derivative notional amount	58,668	[2],[3]	81,678	[2],[3]
Liability derivative fair value	(3,626)	[1],[2],[3]	(10,288)	[1],[2],[3]
Not Designated as Hedging Instrument [Member] | Financial Market Exposure [Member] | Investment Related Derivatives [Member]
Derivatives Fair Value [Line Items]
Asset derivative notional amount	43,578		23,874
Asset derivative fair value	718	[1]	615	[1]
Liability derivative notional amount	15,476		14,321
Liability derivative fair value	(597)	[1]	0	[1]
Not Designated as Hedging Instrument [Member] | Guaranteed Minimum Income Benefit Contract [Member] | Other Non Investment Derivatives [Member]
Derivatives Fair Value [Line Items]
Asset derivative notional amount	0		0
Asset derivative fair value	0	[1]	0	[1]
Liability derivative notional amount	70,352		78,777
Liability derivative fair value	(21,404)	[1]	(22,490)	[1]
Not Designated as Hedging Instrument [Member] | Modified Coinsurance Funds Withheld Contract [Member] | Other Non Investment Derivatives [Member]
Derivatives Fair Value [Line Items]
Asset derivative notional amount	73,929		77,200
Asset derivative fair value	0	[1]	0	[1]
Liability derivative notional amount	0		0
Liability derivative fair value	$ 0	[1]	$ 0	[1]

[1] Derivative instruments in an asset or liability position are included within Other assets or Other liabilities, respectively, in the balance sheet.

[2] The Company held net cash collateral related to these derivative positions that is included within Cash and cash equivalents and the corresponding liability to return the collateral has been offset against the derivative asset within the balance sheet as appropriate under the netting agreement.

[3] Financial operations derivatives represent interests in variable interest entities as described in Note 10, "Variable Interest Entities".