Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Other comprehensive income (loss):
Other comprehensive loss, before tax	$ (159,010)	$ (45,516)	$ (556,416)	$ (70,704)
Other comprehensive income (loss):
Other comprehensive income, tax effect	22,000	8,599	82,132	10,944
Net of Tax
Balance, beginning of period			4,236,114
Other comprehensive income (loss):
Total other comprehensive income (loss)	(137,010)	(36,917)	(474,284)	(59,760)
Balance, end of period	4,294,208	4,167,984	4,294,208	4,167,984
Accumulated Other Comprehensive Income (Loss)
Before Tax
AOCI before tax, beginning of period	(332,126)	143,136	65,280	168,324
Other comprehensive income (loss):
AOCI before tax, end of period	(491,136)	97,620	(491,136)	97,620
Tax Effect
AOCI tax effect, beginning of period	45,559	(27,705)	(14,573)	(30,050)
Other comprehensive income (loss):
AOCI tax effect, end of period	67,559	(19,106)	67,559	(19,106)
Net of Tax
Balance, beginning of period	(286,567)	115,431	50,707	138,274
Other comprehensive income (loss):
Total other comprehensive income (loss)	(137,010)	(36,917)	(474,284)	(59,760)
Balance, end of period	(423,577)	78,514	(423,577)	78,514
Accumulated Net Investment Gains (Losses) On Investments
Other comprehensive income (loss):
Unrealized holding gains (losses) arising during the period	(158,835)	(45,295)	(564,064)	(70,095)
Less: Reclassification adjustment for losses (gains) included in net income, before tax	(175)	(221)	7,648	(609)
Other comprehensive loss, before tax	(159,010)	(45,516)	(556,416)	(70,704)
Other comprehensive income (loss):
Unrealized holding gains (losses) arising during the period	21,899	8,548	81,051	10,923
Less: Reclassification adjustment for losses (gains) included in net income, tax effect	101	51	1,081	21
Other comprehensive income, tax effect	22,000	8,599	82,132	10,944
Other comprehensive income (loss):
Unrealized holding gains (losses) arising during the period	(136,936)	(36,747)	(483,013)	(59,172)
Less: Reclassification adjustment for losses (gains) included in net income, net of tax	(74)	(170)	8,729	(588)
Total other comprehensive income (loss)	$ (137,010)	$ (36,917)	$ (474,284)	$ (59,760)

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