Redeemable Noncontrolling Interests - MT. Logan RE (Activity For Redeemable Noncontrolling Interests) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Redeemable Noncontrolling Interest [Line Items]
Redeemable noncontrolling interests - Mt. Logan Re, beginning of period			$ 421,552
Net income (loss) attributable to noncontrolling interests	$ 26,415	$ 7,741	42,507	$ 15,830
Dividends paid on third party investment in redeemable noncontrolling interest			(41,178)
Redeemable noncontrolling interests - Mt. Logan Re, end of period	759,729		759,729		$ 421,552
Logan Re [Member]
Redeemable Noncontrolling Interest [Line Items]
Redeemable noncontrolling interests - Mt. Logan Re, beginning of period			421,552	$ 93,378	93,378
Unaffiliated third party investments during period, net			336,848		279,200
Net income (loss) attributable to noncontrolling interests			42,507		59,307
Dividends paid on third party investment in redeemable noncontrolling interest			(41,178)		(10,334)
Redeemable noncontrolling interests - Mt. Logan Re, end of period	$ 759,729		$ 759,729		$ 421,552