Income Taxes - Reconciliation of Income Tax Expense (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Computed at the statutory rate	$ 20,859	$ 17,539	$ 57,336	$ 53,719
State income taxes, net of federal tax benefit	1,477	1,143	4,855	5,502
Stock-based compensation	(22)	74	15	143
Tax exempt interest income	(2,973)	(1,752)	(8,224)	(4,594)
Tax exempt earnings on BOLI	(435)	(308)	(995)	(839)
Federal tax credits	(491)	(434)	(1,670)	(1,252)
Other differences, net	355	1,371	(1,166)	1,241
Actual tax provision	$ 18,770	$ 17,633	$ 50,151	$ 53,920

Income tax rate reconciliation on tax exempt interest income.

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Income tax rate reconciliation on cash value changes in bank owned life insurance.

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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The amount of income tax expense or benefit for the period computed by applying the domestic federal statutory tax rates to pretax income from continuing operations.

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Amount of reported income tax expense (benefit) in excess of (less than) expected income tax expense (benefit) computed by applying domestic federal statutory income tax rate to pretax income (loss) from continuing operation, attributable to nondeductible expense for award under share-based payment arrangement. Includes, but is not limited to, expense determined to be nondeductible upon grant or after for award under share-based payment arrangement.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to other adjustments.

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