Investments (Reclassifications of AOCI) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Cash flow hedges - Currency/Interest rate
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI	$ 1,213	$ 2,981	$ 3,985	$ 4,259
Net unrealized investments gains (losses) on available-for-sale securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI	(2,730)	2,090	68,175	4,856
Total net unrealized investment gains (losses)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI	(1,517)	5,071	72,160	9,115
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI	$ (1,517)	$ 5,071	$ 72,160	$ 9,115