Income Taxes - Summary of Effective Income Tax Rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Expected federal income tax expense (benefit)	$ 250,796	$ 231,443	$ 267,668
Low income housing investments	(14,291)	(11,443)	(12,115)
Share-based awards	(4,724)	(5,251)	(5,597)
Tax-exempt investment income	(9,644)	(8,961)	(6,977)
Other	1,374	1,937	518
Income tax expense (benefit)	$ 223,511	$ 207,725	$ 243,497
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Expected federal income tax expense (benefit)	21.00%	21.00%	21.00%
Low income housing investments	(1.20%)	(1.10%)	(1.00%)
Share-based awards	(0.40%)	(0.50%)	(0.40%)
Tax-exempt investment income	(0.80%)	(0.80%)	(0.50%)
Other	0.10%	0.20%	0.00%
Income tax expense (benefit)	18.70%	18.80%	19.10%