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Income Taxes - Reconciliation of Tax Expense at the Federal Statutory Tax Rate (Detail) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Income Tax Disclosure [Abstract] |  |  |
Tax expense at the federal statutory tax rate | $ 35,377 | $ 33,546 | $ 47,708
Increase (decrease) in tax expense from: |  |  |
Tax-exempt income, net | (581) | (510) | (829)
Modified endowment life contracts | (519) | (558) | (921)
Share based compensation excess tax benefit | (765) | (917) | (2,354)
State tax expense, net of federal tax benefit | 5,757 | 5,595 | 3,840
Write-down of net deferred tax asset |  |  | 4,331
Utilization of tax credits: |  |  |
New markets tax credits, net of tax expense | (3,547) | (1,422) | (1,151)
Low-income housing tax credits, net of amortization | (1,266) | (1,273) | (1,589)
Other, net | 227 | (523) | 831
Total income taxes | $ 34,683 | $ 33,938 | $ 49,866

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