Income Taxes - Reconciliation of Income Tax Computed at Applicable Federal Statutory Income Tax Rates to Total Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Income Tax Disclosure [Abstract]
Income before income taxes	$ 15,620	$ 17,843
Income taxes computed at Federal statutory tax rate	5,467	6,245
Effect of:
State taxes (net of federal benefit)	470	452
Tax-exempt interest income, net	(170)	(489)
Contingent value right expense (CVR)	0	0
Other, net	13	246
Total income tax expense	$ 5,780	$ 6,454