Allowance for Loan Losses, Allowance for Losses on Lending-Related Commitments and Impaired Loans (Summary Of The Post-Modification Balance Of Loans Restructured) (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
Financing Receivable, Modifications [Line Items]
Restructured loans	$ 4,003	[1],[2]	$ 9,516	[1],[2]	$ 20,748	[1],[2]	$ 69,853	[1],[2]	$ 23,407	[1],[3]	$ 114,404	[1],[3]
Troubled debt restructuring modifications, number of count	4	[1],[2]	18	[1],[2]	30	[1],[2]	68	[1],[2]	37	[1],[3]	121	[1],[3]
Residential real estate and other
Financing Receivable, Modifications [Line Items]
Restructured loans	1,000	[1],[2]	437	[1],[2]	1,778	[1],[2]	1,512	[1],[2]	1,904	[1],[3]	3,977	[1],[3]
Troubled debt restructuring modifications, number of count	1	[1],[2]	4	[1],[2]	8	[1],[2]	9	[1],[2]	9	[1],[3]	16	[1],[3]
Extension at Below Market Terms [Member]
Financing Receivable, Modifications [Line Items]
Restructured loans	4,003	[1]	6,590	[1]	19,930	[1]	56,267	[1]
Troubled debt restructuring modifications, number of count	4	[1]	10	[1]	25	[1]	53	[1]
Extension at Below Market Terms [Member] | Residential real estate and other
Financing Receivable, Modifications [Line Items]
Restructured loans	1,000	[1]	308	[1]	1,095	[1]	1,264	[1]
Troubled debt restructuring modifications, number of count	1	[1]	3	[1]	4	[1]	7	[1]
Reduction of Interest Rate [Member]
Financing Receivable, Modifications [Line Items]
Restructured loans	556	[1]	3,708	[1]	7,545	[1]	59,581	[1]
Troubled debt restructuring modifications, number of count	1	[1]	11	[1]	18	[1]	46	[1]
Reduction of Interest Rate [Member] | Residential real estate and other
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1]	357	[1]	762	[1]	504	[1]
Troubled debt restructuring modifications, number of count	0	[1]	3	[1]	6	[1]	5	[1]
Modification to Interest Only Payments [Member]
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1]	8,475	[1]	6,539	[1]	56,383	[1]
Troubled debt restructuring modifications, number of count	0	[1]	11	[1]	7	[1]	41	[1]
Modification to Interest Only Payments [Member] | Residential real estate and other
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1]	79	[1]	234	[1]	924	[1]
Troubled debt restructuring modifications, number of count	0	[1]	1	[1]	2	[1]	3	[1]
Forgiveness of Debt [Member]
Financing Receivable, Modifications [Line Items]
Restructured loans	1,000	[1]	0	[1]	1,073	[1]	1,515	[1]
Troubled debt restructuring modifications, number of count	1	[1]	0	[1]	2	[1]	3	[1]
Forgiveness of Debt [Member] | Residential real estate and other
Financing Receivable, Modifications [Line Items]
Restructured loans	1,000	[1]	0	[1]	1,000	[1]	29	[1]
Troubled debt restructuring modifications, number of count	1	[1]	0	[1]	1	[1]	1	[1]
Commercial and industrial | Commercial
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1],[2]	442	[1],[2]	708	[1],[2]	13,325	[1],[2]	1,694	[1],[3]	15,161	[1],[3]
Troubled debt restructuring modifications, number of count	0	[1],[2]	3	[1],[2]	6	[1],[2]	16	[1],[2]	8	[1],[3]	21	[1],[3]
Commercial and industrial | Extension at Below Market Terms [Member] | Commercial
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1]	275	[1]	573	[1]	2,617	[1]
Troubled debt restructuring modifications, number of count	0	[1]	2	[1]	5	[1]	9	[1]
Commercial and industrial | Reduction of Interest Rate [Member] | Commercial
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1]	225	[1]	553	[1]	12,705	[1]
Troubled debt restructuring modifications, number of count	0	[1]	1	[1]	4	[1]	9	[1]
Commercial and industrial | Modification to Interest Only Payments [Member] | Commercial
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1]	167	[1]	185	[1]	10,579	[1]
Troubled debt restructuring modifications, number of count	0	[1]	1	[1]	2	[1]	7	[1]
Commercial and industrial | Forgiveness of Debt [Member] | Commercial
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1]	0	[1]	0	[1]	1,486	[1]
Troubled debt restructuring modifications, number of count	0	[1]	0	[1]	0	[1]	2	[1]
Residential construction | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1],[2]	496	[1],[2]	0	[1],[2]	2,147	[1],[2]	0	[1],[3]	3,252	[1],[3]
Troubled debt restructuring modifications, number of count	0	[1],[2]	1	[1],[2]	0	[1],[2]	3	[1],[2]	0	[1],[3]	4	[1],[3]
Residential construction | Extension at Below Market Terms [Member] | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1]	496	[1]	0	[1]	2,147	[1]
Troubled debt restructuring modifications, number of count		[1]	1	[1]	0	[1]	3	[1]
Residential construction | Reduction of Interest Rate [Member] | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1]	496	[1]	0	[1]	496	[1]
Troubled debt restructuring modifications, number of count	0	[1]	1	[1]	0	[1]	1	[1]
Residential construction | Modification to Interest Only Payments [Member] | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1]	496	[1]	0	[1]	496	[1]
Troubled debt restructuring modifications, number of count	0	[1]	1	[1]	0	[1]	1	[1]
Residential construction | Forgiveness of Debt [Member] | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1]	0	[1]	0	[1]	0	[1]
Troubled debt restructuring modifications, number of count	0	[1]	0	[1]	0	[1]	0	[1]
Commercial construction | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1],[2]	0	[1],[2]	6,120	[1],[2]	622	[1],[2]	6,120	[1],[3]	3,360	[1],[3]
Troubled debt restructuring modifications, number of count	0	[1],[2]	0	[1],[2]	3	[1],[2]	2	[1],[2]	3	[1],[3]	7	[1],[3]
Commercial construction | Extension at Below Market Terms [Member] | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1]	0	[1]	6,120	[1]	622	[1]
Troubled debt restructuring modifications, number of count	0	[1]	0	[1]	3	[1]	2	[1]
Commercial construction | Reduction of Interest Rate [Member] | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1]	0	[1]	0	[1]	622	[1]
Troubled debt restructuring modifications, number of count	0	[1]	0	[1]	0	[1]	2	[1]
Commercial construction | Modification to Interest Only Payments [Member] | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1]	0	[1]	6,120	[1]	622	[1]
Troubled debt restructuring modifications, number of count	0	[1]	0	[1]	3	[1]	2	[1]
Commercial construction | Forgiveness of Debt [Member] | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1]	0	[1]	0	[1]	0	[1]
Troubled debt restructuring modifications, number of count	0	[1]	0	[1]	0	[1]	0	[1]
Land | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	2,352	[1],[2]	0	[1],[2]	2,639	[1],[2]	31,836	[1],[2]	2,639	[1],[3]	37,860	[1],[3]
Troubled debt restructuring modifications, number of count	1	[1],[2]	0	[1],[2]	3	[1],[2]	17	[1],[2]	3	[1],[3]	21	[1],[3]
Land | Extension at Below Market Terms [Member] | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	2,352	[1]	0	[1]	2,639	[1]	31,836	[1]
Troubled debt restructuring modifications, number of count	1	[1]	0	[1]	3	[1]	17	[1]
Land | Reduction of Interest Rate [Member] | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1]	0	[1]	287	[1]	30,561	[1]
Troubled debt restructuring modifications, number of count	0	[1]	0	[1]	2	[1]	14	[1]
Land | Modification to Interest Only Payments [Member] | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1]	0	[1]	0	[1]	26,511	[1]
Troubled debt restructuring modifications, number of count	0	[1]	0	[1]	0	[1]	13	[1]
Land | Forgiveness of Debt [Member] | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1]	0	[1]	73	[1]	0	[1]
Troubled debt restructuring modifications, number of count	0	[1]	0	[1]	1	[1]	0	[1]
Office | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	556	[1],[2]	0	[1],[2]	4,021	[1],[2]	0	[1],[2]	4,021	[1],[3]	4,795	[1],[3]
Troubled debt restructuring modifications, number of count	1	[1],[2]	0	[1],[2]	4	[1],[2]	0	[1],[2]	4	[1],[3]	2	[1],[3]
Office | Extension at Below Market Terms [Member] | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	556	[1]	0	[1]	4,021	[1]	0	[1]
Troubled debt restructuring modifications, number of count	1	[1]	0	[1]	4	[1]	0	[1]
Office | Reduction of Interest Rate [Member] | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	556	[1]	0	[1]	556	[1]	0	[1]
Troubled debt restructuring modifications, number of count	1	[1]	0	[1]	1	[1]	0	[1]
Office | Modification to Interest Only Payments [Member] | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1]	0	[1]	0	[1]	0	[1]
Troubled debt restructuring modifications, number of count	0	[1]	0	[1]	0	[1]	0	[1]
Office | Forgiveness of Debt [Member] | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1]	0	[1]	0	[1]	0	[1]
Troubled debt restructuring modifications, number of count	0	[1]	0	[1]	0	[1]	0	[1]
Industrial | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1],[2]	0	[1],[2]	949	[1],[2]	0	[1],[2]	1,676	[1],[3]	1,313	[1],[3]
Troubled debt restructuring modifications, number of count	0	[1],[2]	0	[1],[2]	1	[1],[2]	0	[1],[2]	2	[1],[3]	2	[1],[3]
Industrial | Extension at Below Market Terms [Member] | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1]	0	[1]	949	[1]	0	[1]
Troubled debt restructuring modifications, number of count	0	[1]	0	[1]	1	[1]	0	[1]
Industrial | Reduction of Interest Rate [Member] | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1]	0	[1]	949	[1]	0	[1]
Troubled debt restructuring modifications, number of count	0	[1]	0	[1]	1	[1]	0	[1]
Industrial | Modification to Interest Only Payments [Member] | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1]	0	[1]	0	[1]	0	[1]
Troubled debt restructuring modifications, number of count	0	[1]	0	[1]	0	[1]	0	[1]
Industrial | Forgiveness of Debt [Member] | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1]	0	[1]	0	[1]	0	[1]
Troubled debt restructuring modifications, number of count	0	[1]	0	[1]	0	[1]	0	[1]
Retail | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1],[2]	4,653	[1],[2]	200	[1],[2]	13,286	[1],[2]	431	[1],[3]	28,097	[1],[3]
Troubled debt restructuring modifications, number of count	0	[1],[2]	2	[1],[2]	1	[1],[2]	7	[1],[2]	2	[1],[3]	15	[1],[3]
Retail | Extension at Below Market Terms [Member] | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1]	4,653	[1]	200	[1]	13,286	[1]
Troubled debt restructuring modifications, number of count	0	[1]	2	[1]	1	[1]	7	[1]
Retail | Reduction of Interest Rate [Member] | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1]	0	[1]	200	[1]	8,633	[1]
Troubled debt restructuring modifications, number of count	0	[1]	0	[1]	1	[1]	5	[1]
Retail | Modification to Interest Only Payments [Member] | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1]	4,654	[1]	0	[1]	12,897	[1]
Troubled debt restructuring modifications, number of count	0	[1]	2	[1]	0	[1]	6	[1]
Retail | Forgiveness of Debt [Member] | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1]	0	[1]	0	[1]	0	[1]
Troubled debt restructuring modifications, number of count	0	[1]	0	[1]	0	[1]	0	[1]
Multi-family | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1],[2]	380	[1],[2]	705	[1],[2]	380	[1],[2]	705	[1],[3]	4,247	[1],[3]
Troubled debt restructuring modifications, number of count	0	[1],[2]	1	[1],[2]	1	[1],[2]	1	[1],[2]	1	[1],[3]	6	[1],[3]
Multi-family | Extension at Below Market Terms [Member] | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1]	0	[1]	705	[1]	0	[1]
Troubled debt restructuring modifications, number of count	0	[1]	0	[1]	1	[1]	0	[1]
Multi-family | Reduction of Interest Rate [Member] | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1]	380	[1]	705	[1]	380	[1]
Troubled debt restructuring modifications, number of count	0	[1]	1	[1]	1	[1]	1	[1]
Multi-family | Modification to Interest Only Payments [Member] | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1]	380	[1]	0	[1]	380	[1]
Troubled debt restructuring modifications, number of count	0	[1]	1	[1]	0	[1]	1	[1]
Multi-family | Forgiveness of Debt [Member] | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1]	0	[1]	0	[1]	0	[1]
Troubled debt restructuring modifications, number of count	0	[1]	0	[1]	0	[1]	0	[1]
Mixed use and other | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	95	[1],[2]	3,108	[1],[2]	3,628	[1],[2]	6,745	[1],[2]	4,217	[1],[3]	12,342	[1],[3]
Troubled debt restructuring modifications, number of count	1	[1],[2]	7	[1],[2]	3	[1],[2]	13	[1],[2]	5	[1],[3]	27	[1],[3]
Mixed use and other | Extension at Below Market Terms [Member] | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	95	[1]	858	[1]	3,628	[1]	4,495	[1]
Troubled debt restructuring modifications, number of count	1	[1]	2	[1]	3	[1]	8	[1]
Mixed use and other | Reduction of Interest Rate [Member] | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1]	2,250	[1]	3,533	[1]	5,680	[1]
Troubled debt restructuring modifications, number of count	0	[1]	5	[1]	2	[1]	9	[1]
Mixed use and other | Modification to Interest Only Payments [Member] | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	0	[1]	2,699	[1]	0	[1]	3,974	[1]
Troubled debt restructuring modifications, number of count	0	[1]	5	[1]	0	[1]	8	[1]
Mixed use and other | Forgiveness of Debt [Member] | Commercial real-estate
Financing Receivable, Modifications [Line Items]
Restructured loans	$ 0	[1]	$ 0	[1]	$ 0	[1]	$ 0	[1]
Troubled debt restructuring modifications, number of count	0	[1]	0	[1]	0	[1]	0	[1]

[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.