Derivative Instruments - Net Realized and unrealized gains (losses) on derivative instruments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Derivative [Line Items]
Amount of gain (loss) recognized in income from ineffective portion of fair value hedges	$ 0	$ 0	$ 0	$ (256)
Net realized and unrealized gains (losses) on derivative instruments	(7,903)	5,131	57,127	18,540
Derivatives not designated as hedging instruments
Derivative [Line Items]
Total gain (loss) recognized in income from derivatives not designated as hedging instruments	(7,903)	5,131	57,127	18,796
Derivatives not designated as hedging instruments | Investment related derivatives
Derivative [Line Items]
Interest rate exposure	(5,120)	3,987	(2,046)	13,313
Foreign exchange exposure	(146)	(576)	(1,026)	1,222
Credit exposure	1,684	384	1,380	391
Financial market exposure	(4,309)	(912)	(2,913)	2,467
Derivatives not designated as hedging instruments | Financial operations derivatives
Derivative [Line Items]
Credit exposure	0	915	0	(3,438)
Derivatives not designated as hedging instruments | Other non-investment derivatives
Derivative [Line Items]
Foreign exchange exposure	4,063	0	61,494	0
Credit exposure	(327)	0	1,151	0
Guaranteed minimum income benefit contract	0	0	0	2,257
Modified coinsurance funds withheld contract	(3,748)	1,333	(913)	2,584
Life Funds Withheld Assets
Derivative [Line Items]
Net realized and unrealized gains (losses) on derivative instruments	$ (126,140)	$ (201,264)	$ (116,333)	$ (218,810)