Derivative Instruments - Net Realized and unrealized gains (losses) on Derivative Instruments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Derivative [Line Items]
Amount of gain (loss) recognized in income from ineffective portion of fair value hedges	$ (2,050)	$ (506)	$ (256)	$ 969
Net realized and unrealized gains (losses) on derivative instruments	11,599	(5,105)	13,409	2,780
Derivatives not designated as hedging instruments
Derivative [Line Items]
Total gain (loss) recognized in income from derivatives not designated as hedging instruments	13,649	(4,599)	13,665	1,811
Derivatives not designated as hedging instruments | Investment related derivatives
Derivative [Line Items]
Interest rate exposure	8,978	288	9,326	489
Foreign exchange exposure	(1,490)	(2,690)	1,798	(4,288)
Credit exposure	411	(1,178)	7	(1,994)
Financial market exposure	2,508	(2,736)	3,378	2,616
Derivatives not designated as hedging instruments | Financial operations derivatives
Derivative [Line Items]
Credit exposure	447	1,087	(4,353)	1,329
Derivatives not designated as hedging instruments | Other non-investment derivatives
Derivative [Line Items]
Guaranteed minimum income benefit contract	633	2,306	2,257	6,002
Modified coinsurance funds withheld contract	2,162	(1,676)	1,252	(2,343)
Life Funds Withheld Assets
Derivative [Line Items]
Net realized and unrealized gains (losses) on derivative instruments	$ (17,546)	$ 0	$ (17,546)	$ 0