Commitments and Contingencies - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Commitments and Contingencies Disclosure [Abstract]
Allowance for unfunded commitments	$ 2,500,000	$ 2,300,000
Data processing and communication charges	11,700,000	9,800,000	$ 9,500,000
Data Processing, Contract Termination and Conversion Cost Expenses	$ 1,300,000	$ 0	$ 800,000