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
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Amount Reclassified from AOCI	$ 1,342	$ 606	$ 6,989	$ 1,540
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	8,555	(858)	87,845	3,112
Total net unrealized investment gains (losses)
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Amount Reclassified from AOCI	9,897	(252)	94,834	4,652
Accumulated Other Comprehensive Income (Loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Amount Reclassified from AOCI	$ 9,897	$ (252)	$ 94,834	$ 4,652