Derivative Instruments - Gross amounts of derivative fair values contained in the consolidated balance sheet (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Derivatives, Fair Value [Line Items]
Asset derivative fair value	$ 27,979		$ 23,515
Liability derivative fair value	198,801		65,299
Derivatives designated as hedging instruments | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Asset derivative notional amount	915,109		670,751
Asset derivative fair value	27,024	[1]	12,511	[1]
Liability derivative notional amount	2,766,826		2,382,507
Liability derivative fair value	162,666	[1]	23,715	[1]
Derivatives not designated as hedging instruments
Derivatives, Fair Value [Line Items]
Asset derivative notional amount	184,915		253,183
Asset derivative fair value	3,555	[1]	12,331	[1]
Liability derivative notional amount	559,817		650,411
Liability derivative fair value	38,735	[1]	42,911	[1]
Derivatives not designated as hedging instruments | Investment related derivatives | Interest rate exposure
Derivatives, Fair Value [Line Items]
Asset derivative notional amount	12,715		45,604
Asset derivative fair value	178	[1]	2,060	[1]
Liability derivative notional amount	14,934		26,139
Liability derivative fair value	0	[1]	253	[1]
Derivatives not designated as hedging instruments | Investment related derivatives | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Asset derivative notional amount	69,204		33,007
Asset derivative fair value	2,421	[1]	226	[1]
Liability derivative notional amount	13,507		54,449
Liability derivative fair value	471	[1]	1,790	[1]
Derivatives not designated as hedging instruments | Investment related derivatives | Credit exposure
Derivatives, Fair Value [Line Items]
Asset derivative notional amount	932		25,000
Asset derivative fair value	16	[1]	486	[1]
Liability derivative notional amount	374,088		436,959
Liability derivative fair value	14,855	[1]	15,472	[1]
Derivatives not designated as hedging instruments | Investment related derivatives | Financial market exposure
Derivatives, Fair Value [Line Items]
Asset derivative notional amount	33,838		72,597
Asset derivative fair value	940	[1]	9,559	[1]
Liability derivative notional amount	55,627		16,910
Liability derivative fair value	0	[1]	0	[1]
Derivatives not designated as hedging instruments | Financial operations derivatives | Credit exposure
Derivatives, Fair Value [Line Items]
Asset derivative notional amount	0	[2]	0	[2]
Asset derivative fair value	0	[1],[2]	0	[1],[2]
Liability derivative notional amount	43,482	[2]	46,903	[2]
Liability derivative fair value	4,190	[1],[2]	0	[1],[2]
Derivatives not designated as hedging instruments | Other non-investment derivatives | Guaranteed minimum income benefit contract
Derivatives, Fair Value [Line Items]
Asset derivative notional amount	0		0
Asset derivative fair value	0	[1]	0	[1]
Liability derivative notional amount	58,179		69,051
Liability derivative fair value	19,219	[1]	25,396	[1]
Derivatives not designated as hedging instruments | Other non-investment derivatives | Modified coinsurance funds withheld contract
Derivatives, Fair Value [Line Items]
Asset derivative notional amount	68,226		76,975
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 on a net basis where the Company has both a legal right of offset and the intentions to settle the contracts on a net basis.

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