Loans and Leases and the Allowance for Credit Losses - Impaired Loans and Leases (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Schedule Of Financial Receivables [Line Items]
Recorded investment	$ 902,980	$ 889,226
Unpaid principal balance	1,091,524	1,083,258
Related allowance	86,455	92,608
Commercial, Financial, Leasing, etc. [Member]
Schedule Of Financial Receivables [Line Items]
Recorded investment	145,420	118,386
Unpaid principal balance	173,080	145,187
Related allowance	21,578	24,614
Commercial Real Estate [Member]
Schedule Of Financial Receivables [Line Items]
Recorded investment	186,092	178,841
Unpaid principal balance	224,524	216,658
Related allowance	15,811	19,520
Residential Builder and Developer [Member]
Schedule Of Financial Receivables [Line Items]
Recorded investment	99,801	105,677
Unpaid principal balance	146,979	159,890
Related allowance	4,746	4,379
Other commercial construction [Member]
Schedule Of Financial Receivables [Line Items]
Recorded investment	82,855	93,629
Unpaid principal balance	90,696	102,008
Related allowance	5,933	4,022
Residential [Member]
Schedule Of Financial Receivables [Line Items]
Recorded investment	177,357	180,652
Unpaid principal balance	206,433	209,879
Related allowance	5,262	7,146
Residential Alt-A [Member]
Schedule Of Financial Receivables [Line Items]
Recorded investment	138,033	140,268
Unpaid principal balance	175,320	176,739
Related allowance	13,000	14,000
Home equity lines and loans [Member]
Schedule Of Financial Receivables [Line Items]
Recorded investment	17,522	13,672
Unpaid principal balance	18,592	14,796
Related allowance	5,225	3,312
Automobile [Member]
Schedule Of Financial Receivables [Line Items]
Recorded investment	38,068	40,441
Unpaid principal balance	38,068	40,441
Related allowance	10,120	11,074
Other [Member]
Schedule Of Financial Receivables [Line Items]
Recorded investment	17,832	17,660
Unpaid principal balance	17,832	17,660
Related allowance	4,780	4,541
Impaired Financing Receivable With Related Allowance [Member]
Schedule Of Financial Receivables [Line Items]
Recorded investment	592,581	603,626
Unpaid principal balance	688,054	702,000
Related allowance	86,455	92,608
Impaired Financing Receivable With Related Allowance [Member] | Commercial, Financial, Leasing, etc. [Member]
Schedule Of Financial Receivables [Line Items]
Recorded investment	104,878	90,293
Unpaid principal balance	130,132	112,092
Related allowance	21,578	24,614
Impaired Financing Receivable With Related Allowance [Member] | Commercial Real Estate [Member]
Schedule Of Financial Receivables [Line Items]
Recorded investment	102,898	113,570
Unpaid principal balance	120,165	132,325
Related allowance	15,811	19,520
Impaired Financing Receivable With Related Allowance [Member] | Residential Builder and Developer [Member]
Schedule Of Financial Receivables [Line Items]
Recorded investment	31,314	33,311
Unpaid principal balance	45,625	55,122
Related allowance	4,746	4,379
Impaired Financing Receivable With Related Allowance [Member] | Other commercial construction [Member]
Schedule Of Financial Receivables [Line Items]
Recorded investment	77,054	86,260
Unpaid principal balance	81,296	90,515
Related allowance	5,933	4,022
Impaired Financing Receivable With Related Allowance [Member] | Residential [Member]
Schedule Of Financial Receivables [Line Items]
Recorded investment	93,029	96,508
Unpaid principal balance	112,025	114,521
Related allowance	5,262	7,146
Impaired Financing Receivable With Related Allowance [Member] | Residential Alt-A [Member]
Schedule Of Financial Receivables [Line Items]
Recorded investment	109,986	111,911
Unpaid principal balance	124,319	124,528
Related allowance	13,000	14,000
Impaired Financing Receivable With Related Allowance [Member] | Home equity lines and loans [Member]
Schedule Of Financial Receivables [Line Items]
Recorded investment	17,522	13,672
Unpaid principal balance	18,592	14,796
Related allowance	5,225	3,312
Impaired Financing Receivable With Related Allowance [Member] | Automobile [Member]
Schedule Of Financial Receivables [Line Items]
Recorded investment	38,068	40,441
Unpaid principal balance	38,068	40,441
Related allowance	10,120	11,074
Impaired Financing Receivable With Related Allowance [Member] | Other [Member]
Schedule Of Financial Receivables [Line Items]
Recorded investment	17,832	17,660
Unpaid principal balance	17,832	17,660
Related allowance	4,780	4,541
Impaired Financing Receivable with No Related Allowance [Member]
Schedule Of Financial Receivables [Line Items]
Recorded investment	310,399	285,600
Unpaid principal balance	403,470	381,258
Impaired Financing Receivable with No Related Allowance [Member] | Commercial, Financial, Leasing, etc. [Member]
Schedule Of Financial Receivables [Line Items]
Recorded investment	40,542	28,093
Unpaid principal balance	42,948	33,095
Impaired Financing Receivable with No Related Allowance [Member] | Commercial Real Estate [Member]
Schedule Of Financial Receivables [Line Items]
Recorded investment	83,194	65,271
Unpaid principal balance	104,359	84,333
Impaired Financing Receivable with No Related Allowance [Member] | Residential Builder and Developer [Member]
Schedule Of Financial Receivables [Line Items]
Recorded investment	68,487	72,366
Unpaid principal balance	101,354	104,768
Impaired Financing Receivable with No Related Allowance [Member] | Other commercial construction [Member]
Schedule Of Financial Receivables [Line Items]
Recorded investment	5,801	7,369
Unpaid principal balance	9,400	11,493
Impaired Financing Receivable with No Related Allowance [Member] | Residential [Member]
Schedule Of Financial Receivables [Line Items]
Recorded investment	84,328	84,144
Unpaid principal balance	94,408	95,358
Impaired Financing Receivable with No Related Allowance [Member] | Residential Alt-A [Member]
Schedule Of Financial Receivables [Line Items]
Recorded investment	28,047	28,357
Unpaid principal balance	$ 51,001	$ 52,211