Stock-based Compensation - Summary of Information with Respect to Stock-Based Compensation (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Salaries and employee benefits	$ 1,094	$ 1,044	$ 3,234	$ 2,434
Income tax benefit related to stock-based compensation included in net income	259	465	1,301	1,286
General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
General and administrative expenses	$ 0	$ 0	$ 450	$ 451