Derivative Instruments (Current Period Cash Flow Hedges in AOCI (loss) before Taxes) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
AOCI Cash Flow Hedges [Roll Forward]
Balance beginning	$ (30,598)	$ (4,020)	$ (31,591)	$ (4,578)
Gains (losses) deferred in other comprehensive income (loss) on the effective portion of cash flow hedges	8,735	4,798	8,948	5,574
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(2,038)		(1,258)
Balance ending	(23,901)	457	(23,901)	457
Interest Rate Swap [Member]
AOCI Cash Flow Hedges [Roll Forward]
Gains (losses) deferred in other comprehensive income (loss) on the effective portion of cash flow hedges	2,417	4,798	(5,150)	5,574
Investment Income [Member]
AOCI Cash Flow Hedges [Roll Forward]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(543)		(603)
Investment Income [Member] | Forward Contracts [Member]
AOCI Cash Flow Hedges [Roll Forward]
Gains (losses) deferred in other comprehensive income (loss) on the effective portion of cash flow hedges	0		0
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(312)		(312)
Investment Income [Member] | Interest Rate Swap [Member]
AOCI Cash Flow Hedges [Roll Forward]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(231)	(321)	(291)	(539)
Investment Related Gains Losses [Member] | Forward Contracts [Member]
AOCI Cash Flow Hedges [Roll Forward]
Gains (losses) deferred in other comprehensive income (loss) on the effective portion of cash flow hedges	6,318		14,098
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	$ (1,495)	$ 0	$ (655)	$ 0