Equity (Reclassifications Out of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net investment gains (losses)	$ (737)	$ (1,689)
Net derivative gains (losses)	(131,536)	50,040
Net investment income	21,408	13,600
Income (loss) from continuing operations before provision for income tax	(89,048)	46,678
Total operating expenses	32,474	(14,795)
Net income (loss)	(56,574)	31,883
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income (loss)	(836)	(1,086)
Reclassification out of Accumulated Other Comprehensive Income | Unrealized Investment Gains (Losses), Net of Related Offsets
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net investment gains (losses)	(1,304)	(1,671)
Net investment income	17	0
Income (loss) from continuing operations before provision for income tax	(1,287)	(1,671)
Total operating expenses	451	585
Net income (loss)	$ (836)	$ (1,086)