Investments (Reclassifications of AOCI) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Cash flow hedges—Currency/Interest rate
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Amount Reclassified from AOCI	$ 5,256	$ 702	$ 5,647	$ 934
Net unrealized investment gains (losses) on available-for-sale securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Amount Reclassified from AOCI	81,825	2,340	79,288	3,970
Total net unrealized investment gains (losses)
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Amount Reclassified from AOCI	87,081	3,042	84,935	4,904
Accumulated Other Comprehensive Income (Loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Amount Reclassified from AOCI	$ 87,081	$ 3,042	$ 84,935	$ 4,904