Loans and Leases - Summary of Impaired Loans, by Class (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Financial Receivables Impaired Or Restructured [Line Items]
Unpaid Contractual Principal Balance	$ 80,832	$ 81,765
Recorded Investment With No Specific Reserve	65,577	66,619
Recorded Investment With Specific Reserve	2,731	2,831
Total Recorded Investment	68,308	69,450
Specific Reserve	2,225	1,179
Average Recorded Investment	69,081	75,367
Commercial Real Estate [Member]
Financial Receivables Impaired Or Restructured [Line Items]
Unpaid Contractual Principal Balance	35,137	34,583
Recorded Investment With No Specific Reserve	25,753	25,443
Recorded Investment With Specific Reserve	822	883
Total Recorded Investment	26,575	26,326
Specific Reserve	655	399
Average Recorded Investment	26,301	30,807
Commercial and Industrial [Member]
Financial Receivables Impaired Or Restructured [Line Items]
Unpaid Contractual Principal Balance	10,130	11,412
Recorded Investment With No Specific Reserve	7,325	7,609
Recorded Investment With Specific Reserve	1,909	1,948
Total Recorded Investment	9,234	9,557
Specific Reserve	1,570	780
Average Recorded Investment	9,650	9,510
Commercial Leases [Member]
Financial Receivables Impaired Or Restructured [Line Items]
Unpaid Contractual Principal Balance	699	722
Recorded Investment With No Specific Reserve	699	722
Total Recorded Investment	699	722
Average Recorded Investment	716	686
Total Commercial Loans and Leases [Member]
Financial Receivables Impaired Or Restructured [Line Items]
Unpaid Contractual Principal Balance	45,966	46,717
Recorded Investment With No Specific Reserve	33,777	33,774
Recorded Investment With Specific Reserve	2,731	2,831
Total Recorded Investment	36,508	36,605
Specific Reserve	2,225	1,179
Average Recorded Investment	36,667	41,003
Direct Installment [Member]
Financial Receivables Impaired Or Restructured [Line Items]
Unpaid Contractual Principal Balance	15,043	14,987
Recorded Investment With No Specific Reserve	14,356	14,680
Total Recorded Investment	14,356	14,680
Average Recorded Investment	14,322	14,248
Residential Mortgages [Member]
Financial Receivables Impaired Or Restructured [Line Items]
Unpaid Contractual Principal Balance	14,962	16,791
Recorded Investment With No Specific Reserve	14,472	15,064
Total Recorded Investment	14,472	15,064
Average Recorded Investment	15,076	16,924
Indirect Installment [Member]
Financial Receivables Impaired Or Restructured [Line Items]
Unpaid Contractual Principal Balance	2,782	1,467
Recorded Investment With No Specific Reserve	1,052	1,305
Total Recorded Investment	1,052	1,305
Average Recorded Investment	1,208	1,399
Consumer Lines of Credit [Member]
Financial Receivables Impaired Or Restructured [Line Items]
Unpaid Contractual Principal Balance	2,079	1,803
Recorded Investment With No Specific Reserve	1,920	1,796
Total Recorded Investment	1,920	1,796
Average Recorded Investment	$ 1,808	$ 1,793