Allowance for Loan Losses, Allowance for Losses on Lending-Related Commitments and Impaired Loans (Summary Of Loans Restructured And Subsequently Defaulted Under The Restructured Terms) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended				12 Months Ended
	Sep. 30, 2013 Loan		Sep. 30, 2012 Loan		Sep. 30, 2013 Loan		Sep. 30, 2012 Loan		Sep. 30, 2013 Loan		Sep. 30, 2012 Loan
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Total, Count	4	[1],[2]	18	[1],[2]	30	[1],[2]	68	[1],[2]	37	[1],[3]	121	[1],[3]
Total, Balance	$ 4,003	[1],[2]	$ 9,516	[1],[2]	$ 20,748	[1],[2]	$ 69,853	[1],[2]	$ 23,407	[1],[3]	$ 114,404	[1],[3]
Payments in Default, Count	6	[1],[4]	18	[1],[4]	9	[1],[4]	24	[1],[4]
Payments in Default, Balance	2,972	[1],[4]	7,841	[1],[4]	3,970	[1],[4]	13,451	[1],[4]
Commercial | Commercial and industrial
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Total, Count	0	[1],[2]	3	[1],[2]	6	[1],[2]	16	[1],[2]	8	[1],[3]	21	[1],[3]
Total, Balance	0	[1],[2]	442	[1],[2]	708	[1],[2]	13,325	[1],[2]	1,694	[1],[3]	15,161	[1],[3]
Payments in Default, Count	1	[1],[4]	3	[1],[4]	2	[1],[4]	3	[1],[4]
Payments in Default, Balance	161	[1],[4]	351	[1],[4]	181	[1],[4]	351	[1],[4]
Commercial real-estate | Residential construction
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Total, Count	0	[1],[2]	1	[1],[2]	0	[1],[2]	3	[1],[2]	0	[1],[3]	4	[1],[3]
Total, Balance	0	[1],[2]	496	[1],[2]	0	[1],[2]	2,147	[1],[2]	0	[1],[3]	3,252	[1],[3]
Payments in Default, Count	0	[1],[4]	0	[1],[4]	0	[1],[4]	0	[1],[4]
Payments in Default, Balance	0	[1],[4]	0	[1],[4]	0	[1],[4]	0	[1],[4]
Commercial real-estate | Commercial construction
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Total, Count	0	[1],[2]	0	[1],[2]	3	[1],[2]	2	[1],[2]	3	[1],[3]	7	[1],[3]
Total, Balance	0	[1],[2]	0	[1],[2]	6,120	[1],[2]	622	[1],[2]	6,120	[1],[3]	3,360	[1],[3]
Payments in Default, Count	0	[1],[4]	5	[1],[4]	0	[1],[4]	5	[1],[4]
Payments in Default, Balance	0	[1],[4]	2,740	[1],[4]	0	[1],[4]	2,740	[1],[4]
Commercial real-estate | Land
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Total, Count	1	[1],[2]	0	[1],[2]	3	[1],[2]	17	[1],[2]	3	[1],[3]	21	[1],[3]
Total, Balance	2,352	[1],[2]	0	[1],[2]	2,639	[1],[2]	31,836	[1],[2]	2,639	[1],[3]	37,860	[1],[3]
Payments in Default, Count	1	[1],[4]	1	[1],[4]	1	[1],[4]	2	[1],[4]
Payments in Default, Balance	215	[1],[4]	651	[1],[4]	215	[1],[4]	1,925	[1],[4]
Commercial real-estate | Office
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Total, Count	1	[1],[2]	0	[1],[2]	4	[1],[2]	0	[1],[2]	4	[1],[3]	2	[1],[3]
Total, Balance	556	[1],[2]	0	[1],[2]	4,021	[1],[2]	0	[1],[2]	4,021	[1],[3]	4,795	[1],[3]
Payments in Default, Count	1	[1],[4]	0	[1],[4]	1	[1],[4]	0	[1],[4]
Payments in Default, Balance	1,648	[1],[4]	0	[1],[4]	1,648	[1],[4]	0	[1],[4]
Commercial real-estate | Industrial
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Total, Count	0	[1],[2]	0	[1],[2]	1	[1],[2]	0	[1],[2]	2	[1],[3]	2	[1],[3]
Total, Balance	0	[1],[2]	0	[1],[2]	949	[1],[2]	0	[1],[2]	1,676	[1],[3]	1,313	[1],[3]
Payments in Default, Count	1	[1],[4]	1	[1],[4]	1	[1],[4]	1	[1],[4]
Payments in Default, Balance	727	[1],[4]	990	[1],[4]	727	[1],[4]	990	[1],[4]
Commercial real-estate | Retail
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Total, Count	0	[1],[2]	2	[1],[2]	1	[1],[2]	7	[1],[2]	2	[1],[3]	15	[1],[3]
Total, Balance	0	[1],[2]	4,653	[1],[2]	200	[1],[2]	13,286	[1],[2]	431	[1],[3]	28,097	[1],[3]
Payments in Default, Count	0	[1],[4]	0	[1],[4]	0	[1],[4]	1	[1],[4]
Payments in Default, Balance	0	[1],[4]	0	[1],[4]	0	[1],[4]	1,605	[1],[4]
Commercial real-estate | Multi-family
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Total, Count	0	[1],[2]	1	[1],[2]	1	[1],[2]	1	[1],[2]	1	[1],[3]	6	[1],[3]
Total, Balance	0	[1],[2]	380	[1],[2]	705	[1],[2]	380	[1],[2]	705	[1],[3]	4,247	[1],[3]
Payments in Default, Count	0	[1],[4]	1	[1],[4]	1	[1],[4]	1	[1],[4]
Payments in Default, Balance	0	[1],[4]	264	[1],[4]	705	[1],[4]	264	[1],[4]
Commercial real-estate | Mixed use and other
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Total, Count	1	[1],[2]	7	[1],[2]	3	[1],[2]	13	[1],[2]	5	[1],[3]	27	[1],[3]
Total, Balance	95	[1],[2]	3,108	[1],[2]	3,628	[1],[2]	6,745	[1],[2]	4,217	[1],[3]	12,342	[1],[3]
Payments in Default, Count	1	[1],[4]	2	[1],[4]	2	[1],[4]	5	[1],[4]
Payments in Default, Balance	95	[1],[4]	914	[1],[4]	368	[1],[4]	3,197	[1],[4]
Residential real estate and other
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Total, Count	1	[1],[2]	4	[1],[2]	8	[1],[2]	9	[1],[2]	9	[1],[3]	16	[1],[3]
Total, Balance	1,000	[1],[2]	437	[1],[2]	1,778	[1],[2]	1,512	[1],[2]	1,904	[1],[3]	3,977	[1],[3]
Payments in Default, Count	1	[1],[4]	5	[1],[4]	1	[1],[4]	6	[1],[4]
Payments in Default, Balance	$ 126	[1],[4]	$ 1,931	[1],[4]	$ 126	[1],[4]	$ 2,379	[1],[4]

[1] Balances represent the recorded investment in the loan at the time of the restructuring.

[2] TDRs may have more than one modification representing a concession. As such, TDRs during the period may be represented in more than one of the categories noted above.

[3] Total TDRs represent all loans restructured in TDRs during the previous twelve months from the date indicated.

[4] TDRs considered to be in payment default are over 30 days past-due subsequent to the restructuring.