Income Taxes - Reconciliation of Income Tax Expense (Benefit) Attributable to Income from Operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Reconciliation of income tax expense reported to amount computed by applying the U.S. federal tax rate
Provision for income taxes at the statutory federal rate	$ 33,021	$ 24,533	$ 82,402	$ 79,825
Increase (reduction) in taxes resulting from:
Excess tax benefit on share-based compensation	(50)	(1,967)	(3,208)	(4,264)
Tax exempt interest income	(144)	(216)	(476)	(725)
Dividends received deduction	(253)	(588)	(752)	(1,056)
Tax credit	(645)	(1,093)	(1,935)	(2,629)
ESOP dividends paid deduction	(158)	(149)	(466)	(439)
Nondeductible expenses	1,367	1,160	2,933	2,819
Other items, net	(503)	118	1,733	1,669
Income tax expense	$ 32,635	$ 21,798	$ 80,231	$ 75,200
Reconciliation of income tax expense rate to the U.S. federal tax rate
Tax rate used (as a percent)	21.00%	21.00%	21.00%	21.00%
Excess tax benefit on share-based compensation (as a percent)	0.00%	(1.70%)	(0.80%)	(1.10%)
Effective rate reduction due to tax exempt interest income (as a percent)	(0.10%)	(0.20%)	(0.10%)	(0.20%)
Effective rate reduction due to dividend received (as a percent)	(0.20%)	(0.50%)	(0.20%)	(0.30%)
Effective rate reduction due to tax credit (as a percent)	(0.40%)	(0.90%)	(0.50%)	(0.70%)
Effective rate reduction due to dividend paid to ESOP (as a percent)	(0.10%)	(0.10%)	(0.10%)	(0.10%)
Effective rate reduction due to nondeductible expenses (as a percent)	0.90%	1.00%	0.70%	0.70%
Effective rate reduction due to other items, net (as a percent)	(0.30%)	0.10%	0.40%	0.50%
Total tax expense (as a percent)	20.80%	18.70%	20.40%	19.80%