Equity (Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			$ 1,533,059
Income tax benefit (expense)	$ (62,230)	$ (51,949)	313,350	$ (320,666)
Ending balance	354,266		354,266
Foreign Currency Translation Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(708)	(934)
Change in OCI before reclassifications			66	(481)
Amounts reclassified from AOCI			0	0
Income tax benefit (expense)			(14)	101
Ending balance	(656)	(1,314)	(656)	(1,314)
Net Unrealized Investment Gains (Losses)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			1,533,767	429,546
Change in OCI before reclassifications			(418,162)	1,563,347
Amounts reclassified from AOCI			(1,074,047)	(35,880)
Income tax benefit (expense)			313,364	(320,767)
Ending balance	354,922	1,636,246	354,922	1,636,246
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			1,533,059	428,612
Change in OCI before reclassifications			(418,096)	1,562,866
Amounts reclassified from AOCI			(1,074,047)	(35,880)
Income tax benefit (expense)			313,350	(320,666)
Ending balance	354,266	1,634,932	354,266	1,634,932
Cash flow hedges | Net Unrealized Investment Gains (Losses)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(43,000)	0
Ending balance	$ (18,000)	$ 68,000	$ (18,000)	$ 68,000