Loans and Leases and the Allowance for Credit Losses - Loan Modification Activities that were Considered Troubled Debt Restructurings (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014 Modification	Mar. 31, 2013 Modification
Financing Receivable, Modifications [Line Items]
Number of modifications	243	332
Pre-modification, Recorded investment	$ 32,530	$ 79,681
Post-modification, Recorded investment	32,500	79,660
Financial effects of modification, Recorded investment	(30)	(21)
Financial effects of modification, Interest	(869)	(884)
Principal deferral [Member] | Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications	30	24
Pre-modification, Recorded investment	14,954	2,006
Post-modification, Recorded investment	14,848	1,982
Financial effects of modification, Recorded investment	(106)	(24)
Financial effects of modification, Interest
Principal deferral [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications	13	8
Pre-modification, Recorded investment	7,044	18,478
Post-modification, Recorded investment	7,002	18,363
Financial effects of modification, Recorded investment	(42)	(115)
Financial effects of modification, Interest
Principal deferral [Member] | Residential Builder and Developer [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications		8
Pre-modification, Recorded investment		1,357
Post-modification, Recorded investment		1,340
Financial effects of modification, Recorded investment		(17)
Financial effects of modification, Interest
Principal deferral [Member] | Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications	13	7
Pre-modification, Recorded investment	1,602	566
Post-modification, Recorded investment	1,663	607
Financial effects of modification, Recorded investment	61	41
Financial effects of modification, Interest
Principal deferral [Member] | Residential Alt-A [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications	2
Pre-modification, Recorded investment	166
Post-modification, Recorded investment	202
Financial effects of modification, Recorded investment	36
Financial effects of modification, Interest
Principal deferral [Member] | Other commercial construction [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications	1
Pre-modification, Recorded investment	151
Post-modification, Recorded investment	151
Financial effects of modification, Recorded investment
Financial effects of modification, Interest
Principal deferral [Member] | Home equity lines and loans [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications	3	2
Pre-modification, Recorded investment	280	79
Post-modification, Recorded investment	280	79
Financial effects of modification, Recorded investment
Financial effects of modification, Interest
Principal deferral [Member] | Automobile [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications	80	121
Pre-modification, Recorded investment	993	1,586
Post-modification, Recorded investment	993	1,586
Financial effects of modification, Recorded investment
Financial effects of modification, Interest
Principal deferral [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications	8	6
Pre-modification, Recorded investment	55	45
Post-modification, Recorded investment	55	45
Financial effects of modification, Recorded investment
Financial effects of modification, Interest
Other [Member] | Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications		1
Pre-modification, Recorded investment		47,200
Post-modification, Recorded investment		47,200
Financial effects of modification, Recorded investment
Financial effects of modification, Interest
Other [Member] | Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications	1	1
Pre-modification, Recorded investment	188	195
Post-modification, Recorded investment	188	195
Financial effects of modification, Recorded investment
Financial effects of modification, Interest
Other [Member] | Automobile [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications	11	17
Pre-modification, Recorded investment	61	159
Post-modification, Recorded investment	61	159
Financial effects of modification, Recorded investment
Financial effects of modification, Interest
Other [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications	1	1
Pre-modification, Recorded investment	45	12
Post-modification, Recorded investment	45	12
Financial effects of modification, Recorded investment
Financial effects of modification, Interest
Combination of concession types [Member] | Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications	2	1
Pre-modification, Recorded investment	41	342
Post-modification, Recorded investment	39	342
Financial effects of modification, Recorded investment	(2)
Financial effects of modification, Interest	(4)
Combination of concession types [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications	1	2
Pre-modification, Recorded investment	346	582
Post-modification, Recorded investment	401	581
Financial effects of modification, Recorded investment	55	(1)
Financial effects of modification, Interest	(104)	(56)
Combination of concession types [Member] | Residential Builder and Developer [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications		1
Pre-modification, Recorded investment		1,701
Post-modification, Recorded investment		1,691
Financial effects of modification, Recorded investment		(10)
Financial effects of modification, Interest
Combination of concession types [Member] | Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications	14	20
Pre-modification, Recorded investment	2,188	2,449
Post-modification, Recorded investment	2,160	2,536
Financial effects of modification, Recorded investment	(28)	87
Financial effects of modification, Interest	(282)	(371)
Combination of concession types [Member] | Residential Alt-A [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications	10	5
Pre-modification, Recorded investment	1,746	907
Post-modification, Recorded investment	1,736	925
Financial effects of modification, Recorded investment	(10)	18
Financial effects of modification, Interest	(61)	(110)
Combination of concession types [Member] | Home equity lines and loans [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications	15	2
Pre-modification, Recorded investment	1,856	211
Post-modification, Recorded investment	1,856	211
Financial effects of modification, Recorded investment
Financial effects of modification, Interest	(172)	(33)
Combination of concession types [Member] | Automobile [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications	23	61
Pre-modification, Recorded investment	250	553
Post-modification, Recorded investment	250	553
Financial effects of modification, Recorded investment
Financial effects of modification, Interest	(26)	(42)
Combination of concession types [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications	14	42
Pre-modification, Recorded investment	466	1,217
Post-modification, Recorded investment	466	1,217
Financial effects of modification, Recorded investment
Financial effects of modification, Interest	(188)	(267)
Interest rate reduction [Member] | Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications	1
Pre-modification, Recorded investment	98
Post-modification, Recorded investment	104
Financial effects of modification, Recorded investment	6
Financial effects of modification, Interest	(32)
Interest rate reduction [Member] | Automobile [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications		2
Pre-modification, Recorded investment		36
Post-modification, Recorded investment		36
Financial effects of modification, Recorded investment
Financial effects of modification, Interest		$ (5)