Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Tax at statutory rate, Amount	$ 29,830	$ 24,843	$ 21,747
Income Tax Reconciliation, Bank Owned Life Insurance Income	(1,883)	(1,894)	(1,926)
Tax-exempt interest income, net, Amount	(2,434)	(2,232)	(2,133)
Tax credits, Amount	0	(61)	(134)
Other, Amount	126	180	126
Total tax provision (benefit), Amount	$ 25,639	$ 20,836	$ 17,680
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Tax at statutory rate, Pretax Income	35.00%	35.00%	35.00%
Income from bank owned life insurance, Pretax Income	(2.00%)	(3.00%)	(3.00%)
Tax-exempt interest income, net, Pretax Income	(3.00%)	(3.00%)	(4.00%)
Tax credits, Pretax Income	(0.00%)	(0.00%)	(0.00%)
Other, Pretax Income	0.00%	0.00%	0.00%
Total tax provision (benefit), Pretax Income	30.00%	29.00%	28.00%

Effective Income Tax Rate Reconciliation Bank Owned Life Insurance

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Income Tax Reconciliation, Bank Owned Life Insurance Income

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

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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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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