Allowance for Loan Losses - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Receivables [Abstract]
Impaired financing receivables	$ 45,650	$ 43,977
Acquired loans that experienced credit deterioration since acquisition	$ 9,900
Minimum period interest and principal of loans past due considered nonperforming (in days)	90 days
Evaluation for impairment of substandard and nonaccrual commercial loans	$ 500