Equity (Reclassification out of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Net Unrealized Investment Gains (Losses)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI	$ (1,093,820)	$ (29,479)
Total reclassifications for the period
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI	(1,093,820)	(29,479)
Reclassification out of Accumulated Other Comprehensive Income | Net Unrealized Investment Gains (Losses)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI	1,093,820	29,479
Reclassification out of Accumulated Other Comprehensive Income | Total reclassifications for the period
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from AOCI	1,093,820	29,479
Reclassification out of Accumulated Other Comprehensive Income | Net unrealized investment gains (losses) on available-for-sale securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net unrealized investment gains (losses)	1,081,504	6,422
Reclassification out of Accumulated Other Comprehensive Income | Currency/Interest Rate | Cash flow hedges
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net unrealized investment gains (losses)	$ 12,316	$ 23,057