Income Taxes - Summary of Effective Income Tax Rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Expected federal income tax expense (benefit)	$ 190,325	$ 191,602	$ 188,304
Low income housing investments	(11,443)	(12,115)	(11,913)
Share-based awards	(5,251)	(5,597)	(5,013)
Tax-exempt investment income	(8,961)	(6,977)	(5,830)
Other	1,937	518	(637)
Income tax expense (benefit)	$ 166,607	$ 167,431	$ 164,911
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%)	(1.30%)	(1.30%)
Share-based awards	(0.60%)	(0.60%)	(0.60%)
Tax-exempt investment income	(1.00%)	(0.80%)	(0.60%)
Other	0.20%	0.10%	(0.10%)
Income tax expense (benefit)	18.40%	18.40%	18.40%