Loans - Impaired Loans (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Related Allowance	$ 64,349	$ 73,541
Recorded Investment With Related Allowance	93,896	117,807
Total Recorded Investment	158,245	191,348
Unpaid Contractual Principal Balance	169,698	225,471
Related Allowance	14,840	23,525
Commercial Real Estate Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Related Allowance	52,524	58,643
Recorded Investment With Related Allowance	47,572	55,995
Total Recorded Investment	100,096	114,638
Unpaid Contractual Principal Balance	104,030	131,705
Related Allowance	6,133	8,676
Consumer Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Related Allowance	263	1,010
Recorded Investment With Related Allowance	2,763	84
Total Recorded Investment	3,026	1,094
Unpaid Contractual Principal Balance	3,127	1,211
Related Allowance		82
Commercial and Industrial [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Related Allowance	5,809	3,806
Recorded Investment With Related Allowance	23,974	43,497
Total Recorded Investment		47,303
Unpaid Contractual Principal Balance	35,236	59,891
Related Allowance		11,032
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Related Allowance	44,591	46,872
Recorded Investment With Related Allowance	39,210	47,973
Total Recorded Investment	83,801	94,845
Unpaid Contractual Principal Balance	86,565	110,227
Related Allowance	5,347	7,874
Construction [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Related Allowance	7,933	11,771
Recorded Investment With Related Allowance	8,362	8,022
Total Recorded Investment	16,295	19,793
Unpaid Contractual Principal Balance	17,465	21,478
Related Allowance	786	802
Residential Mortgage [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Related Allowance	5,753	10,082
Recorded Investment With Related Allowance	19,587	18,231
Total Recorded Investment		28,313
Unpaid Contractual Principal Balance	27,305	32,664
Related Allowance	3,216	3,735
Home Equity [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Related Allowance	263	1,010
Recorded Investment With Related Allowance	2,763	84
Total Recorded Investment		1,094
Unpaid Contractual Principal Balance	3,127	1,211
Related Allowance	446	82
Loans [Member] | Commercial and Industrial [Member] | Commercial and Industrial [Member]
Financing Receivable, Impaired [Line Items]
Total Recorded Investment	29,783
Loans [Member] | Residential Mortgage [Member] | Residential Mortgage [Member]
Financing Receivable, Impaired [Line Items]
Total Recorded Investment	25,340
Loans [Member] | Home Equity [Member] | Consumer [Member]
Financing Receivable, Impaired [Line Items]
Total Recorded Investment	3,026
Allowance for Loan and Lease Losses [Member] | Consumer [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	446
Allowance for Loan and Lease Losses [Member] | Commercial and Industrial [Member] | Commercial and Industrial [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	$ 5,045