Investments - Analysis of net realized gains (losses) and the change in unrealized (losses) gains on investments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Net realized gains (losses): [Abstract]
Net realized gains (losses) on investments	$ 49,967	$ 72,697	$ 102,858	$ 91,926
Excluding Life Funds Withheld Assets
Net realized gains (losses): [Abstract]
Gross realized gains	48,547	118,947	110,845	170,160
Gross realized losses on investments sold	(27,608)	(13,487)	(74,728)	(41,744)
OTTI on investments, net of amounts transferred to other comprehensive income	(16,588)	(24,616)	(27,164)	(28,343)
Net realized gains (losses) on investments	4,351	80,844	8,953	100,073
Life Funds Withheld Assets
Net realized gains (losses): [Abstract]
Gross realized gains	84,641	624	137,769	624
Gross realized losses on investments sold	(16,604)	0	(16,994)	0
OTTI on investments, net of amounts transferred to other comprehensive income	(2,878)	(8,771)	(8,087)	(8,771)
Net unrealized gains (losses) on investments, trading securities	(19,543)	0	(18,783)	0
Net realized gains (losses) on investments	$ 45,616	$ (8,147)	$ 93,905	$ (8,147)