Equity (Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ 347,435
Income tax benefit (expense)	213,458	$ 73,731
Ending Balance	(456,775)
Foreign Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(11,274)	(7,797)
Change in OCI before reclassifications	(1,670)	(5,205)
Amounts reclassified from AOCI	0	0
Income tax benefit (expense)	146	192
Ending Balance	(12,798)	(12,810)
Net unrealized investment gains (losses)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	358,709	553,925
Change in OCI before reclassifications	(1,038,929)	(348,914)
Amounts reclassified from AOCI	22,931	(1,288)
Income tax benefit (expense)	213,312	73,539
Ending Balance	(443,977)	277,262
Accumulated Other Comprehensive   Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	347,435	546,128
Change in OCI before reclassifications	(1,040,599)	(354,119)
Amounts reclassified from AOCI	22,931	(1,288)
Income tax benefit (expense)	213,458	73,731
Ending Balance	(456,775)	264,452
Cash flow hedges | Net unrealized investment gains (losses)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	40,000	(8,000)
Ending Balance	$ 53,000	$ (3,000)