Derivative Instruments - Net Realized and unrealized gains (losses) on Derivative Instruments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Derivative [Line Items]
Amount of gain (loss) recognized in income from ineffective portion of fair value hedges	$ 0	$ (260)	$ (256)	$ 709
Net realized and unrealized gains (losses) on derivative instruments	5,131	880	18,540	3,660
Derivatives not designated as hedging instruments
Derivative [Line Items]
Total gain (loss) recognized in income from derivatives not designated as hedging instruments	5,131	1,140	18,796	2,951
Derivatives not designated as hedging instruments | Investment related derivatives
Derivative [Line Items]
Interest rate exposure	3,987	4,334	13,313	4,822
Foreign exchange exposure	(576)	3,710	1,222	(578)
Credit exposure	384	(956)	391	(2,950)
Financial market exposure	(912)	1,553	2,467	4,170
Derivatives not designated as hedging instruments | Financial operations derivatives
Derivative [Line Items]
Credit exposure	915	(3,980)	(3,438)	(2,651)
Derivatives not designated as hedging instruments | Other non-investment derivatives
Derivative [Line Items]
Guaranteed minimum income benefit contract	0	175	2,257	6,178
Modified coinsurance funds withheld contract	1,333	(3,696)	2,584	(6,040)
Life Funds Withheld Assets
Derivative [Line Items]
Net realized and unrealized gains (losses) on derivative instruments	$ (201,264)	$ 0	$ (218,810)	$ 0