Impaired Loans (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Related Allowance	$ 45,721	$ 38,185
Recorded Investment With Related Allowance	154,542	145,890
Total Recorded Investment housands)	200,263	184,075
Unpaid Contractual Principal Balance	226,227	212,899
Related Allowance	23,931	23,243
Commercial Real Estate
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Related Allowance	32,750	30,994
Recorded Investment With Related Allowance	96,344	76,976
Total Recorded Investment housands)	129,094	107,970
Unpaid Contractual Principal Balance	147,719	119,514
Related Allowance	11,775	8,516
Consumer Loans
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Related Allowance	1,642
Recorded Investment With Related Allowance	264	242
Total Recorded Investment housands)	1,906	242
Unpaid Contractual Principal Balance	2,269	242
Related Allowance	15	45
Commercial and Industrial
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Related Allowance	3,474	6,193
Recorded Investment With Related Allowance	39,514	48,665
Total Recorded Investment housands)	42,988	54,858
Unpaid Contractual Principal Balance	48,081	71,111
Related Allowance	9,051	11,105
Commercial Real Estate
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Related Allowance	25,267	26,741
Recorded Investment With Related Allowance	83,522	56,978
Total Recorded Investment housands)	108,789	83,719
Unpaid Contractual Principal Balance	123,785	91,448
Related Allowance	11,067	7,108
Construction
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Related Allowance	7,483	4,253
Recorded Investment With Related Allowance	12,822	19,998
Total Recorded Investment housands)	20,305	24,251
Unpaid Contractual Principal Balance	23,934	28,066
Related Allowance	708	1,408
Residential Mortgage
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Related Allowance	7,855	998
Recorded Investment With Related Allowance	18,420	20,007
Total Recorded Investment housands)	26,275	21,005
Unpaid Contractual Principal Balance	28,158	22,032
Related Allowance	3,090	3,577
Home Equity
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Related Allowance	1,642
Recorded Investment With Related Allowance	264	242
Total Recorded Investment housands)	1,906	242
Unpaid Contractual Principal Balance	2,269	242
Related Allowance	$ 15	$ 45