Allowance for Loan Losses - Summary of Allowance for Loan Losses (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	$ 48,147	$ 47,911
Charge-offs	(3,628)	(1,451)
Recoveries	814	439
Net (Charge-offs)/ Recoveries	(2,814)	(1,012)
Provision for loan losses	5,014	1,207
Balance at End of Period	50,347	48,106
Commercial Real Estate
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	15,043	20,164
Charge-offs	(54)	(66)
Recoveries	361	103
Net (Charge-offs)/ Recoveries	307	37
Provision for loan losses	(84)	(1,130)
Balance at End of Period	15,266	19,071
Commercial and Industrial
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	10,853	13,668
Charge-offs	(2,694)	(707)
Recoveries	203	114
Net (Charge-offs)/ Recoveries	(2,491)	(593)
Provision for loan losses	6,378	636
Balance at End of Period	14,740	13,711
Commercial Construction
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	12,625	6,093
Charge-offs	0	0
Recoveries	2	1
Net (Charge-offs)/ Recoveries	2	1
Provision for loan losses	(1,802)	775
Balance at End of Period	10,825	6,869
Consumer Real Estate
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	8,400	6,333
Charge-offs	(232)	(375)
Recoveries	164	136
Net (Charge-offs)/ Recoveries	(68)	(239)
Provision for loan losses	(71)	629
Balance at End of Period	8,261	6,723
Other Consumer
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	1,226	1,653
Charge-offs	(648)	(303)
Recoveries	84	85
Net (Charge-offs)/ Recoveries	(564)	(218)
Provision for loan losses	593	297
Balance at End of Period	$ 1,255	$ 1,732