Income Taxes - Schedule of Effective Income Tax Rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Expected federal income tax expense (benefit)	$ 278,594	$ 250,796	$ 231,443
Low-income housing investments	(9,700)	(14,291)	(11,443)
Share-based awards	1,341	(4,724)	(5,251)
Tax-exempt investment income	(9,644)	(9,644)	(8,961)
Other tax credits	(5,000)	0	0
Other	284	1,374	1,937
Income tax expense (benefit)	$ 255,875	$ 223,511	$ 207,725
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Expected federal income tax expense (benefit)	21.00%	21.00%	21.00%
Low-income housing investments	(0.70%)	(1.20%)	(1.10%)
Share-based awards	0.10%	(0.40%)	(0.50%)
Tax-exempt investment income	(0.70%)	(0.80%)	(0.80%)
Other tax credits	(0.40%)	0.00%	0.00%
Other	0.00%	0.10%	0.20%
Income tax expense (benefit)	19.30%	18.70%	18.80%