Derivative Instruments - Net Realized and unrealized gains (losses) on derivative instruments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Derivative [Line Items]
Net realized and unrealized gains (losses) on derivative instruments	$ (3,622)	$ 16,521
Derivatives not designated as hedging instruments | Investment related derivatives
Derivative [Line Items]
Interest rate exposure	781	9,637
Foreign exchange exposure	(670)	(1,362)
Credit exposure	(163)	82
Financial market exposure	(1,010)	3,041
Derivatives not designated as hedging instruments | Other non-investment derivatives
Derivative [Line Items]
Foreign exchange exposure	(1,181)	2,059
Credit exposure	(303)	1,346
Modified coinsurance funds withheld contract	(1,076)	1,718
Life Funds Withheld Assets
Derivative [Line Items]
Net realized and unrealized gains (losses) on derivative instruments	$ (236,080)	$ (229,367)