Loans and Leases - Loan Modification Activities that were Considered Troubled Debt Restructurings (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($) Modification	Dec. 31, 2014 USD ($) Modification	Dec. 31, 2013 USD ($) Modification
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	817	760	1,258
Pre-modification, Recorded Investment	$ 204,800	$ 134,351	$ 258,075
Post-modification, Recorded Investment	198,405	130,190	254,352
Financial Effects of Modification, Recorded Investment	(6,395)	(4,161)	(3,723)
Financial Effects of Modification, Interest	$ (1,851)	$ (2,969)	$ (4,691)
Principal Deferral [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	49	39	27
Pre-modification, Recorded Investment	$ 49,486	$ 19,077	$ 40,639
Post-modification, Recorded Investment	48,388	18,997	40,464
Financial Effects of Modification, Recorded Investment	$ (1,098)	$ (80)	$ (175)
Principal Deferral [Member] | Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	114	95	79
Pre-modification, Recorded Investment	$ 55,621	$ 29,035	$ 16,389
Post-modification, Recorded Investment	50,807	23,628	16,002
Financial Effects of Modification, Recorded Investment	$ (4,814)	$ (5,407)	$ (387)
Principal Deferral [Member] | Residential Builder and Developer [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	2	2	18
Pre-modification, Recorded Investment	$ 10,650	$ 1,639	$ 21,423
Post-modification, Recorded Investment	10,598	$ 1,639	20,577
Financial Effects of Modification, Recorded Investment	$ (52)		$ (846)
Principal Deferral [Member] | Other Commercial Construction [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	4	4	3
Pre-modification, Recorded Investment	$ 368	$ 6,703	$ 590
Post-modification, Recorded Investment	460	6,611	521
Financial Effects of Modification, Recorded Investment	$ 92	$ (92)	$ (69)
Principal Deferral [Member] | Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	58	28	32
Pre-modification, Recorded Investment	$ 6,194	$ 2,710	$ 3,556
Post-modification, Recorded Investment	6,528	2,905	3,821
Financial Effects of Modification, Recorded Investment	$ 334	$ 195	$ 265
Principal Deferral [Member] | Residential Limited Documentation [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	2	6	10
Pre-modification, Recorded Investment	$ 426	$ 880	$ 1,900
Post-modification, Recorded Investment	437	963	1,880
Financial Effects of Modification, Recorded Investment	$ 11	$ 83	$ (20)
Principal Deferral [Member] | Home Equity Lines and Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	8	3	10
Pre-modification, Recorded Investment	$ 2,175	$ 280	$ 859
Post-modification, Recorded Investment	$ 2,175	$ 280	861
Financial Effects of Modification, Recorded Investment			$ 2
Principal Deferral [Member] | Automobile [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	192	208	460
Pre-modification, Recorded Investment	$ 1,818	$ 3,293	$ 6,148
Post-modification, Recorded Investment	$ 1,818	$ 3,293	$ 6,148
Principal Deferral [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	102	33	36
Pre-modification, Recorded Investment	$ 1,995	$ 245	$ 332
Post-modification, Recorded Investment	$ 1,995	$ 245	$ 332
Other [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	3	1	2
Pre-modification, Recorded Investment	$ 4,169	$ 650	$ 449
Post-modification, Recorded Investment	4,087		475
Financial Effects of Modification, Recorded Investment	$ (82)	$ (650)	$ 26
Other [Member] | Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	3	3	4
Pre-modification, Recorded Investment	$ 12,965	$ 29,912	$ 50,433
Post-modification, Recorded Investment	12,827	31,604	50,924
Financial Effects of Modification, Recorded Investment	$ (138)	$ 1,692	$ 491
Other [Member] | Residential Builder and Developer [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification			1
Pre-modification, Recorded Investment			$ 4,039
Post-modification, Recorded Investment			3,888
Financial Effects of Modification, Recorded Investment			$ (151)
Other [Member] | Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	1	1	1
Pre-modification, Recorded Investment	$ 267	$ 188	$ 195
Post-modification, Recorded Investment	$ 267	$ 188	$ 195
Other [Member] | Home Equity Lines and Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification			1
Pre-modification, Recorded Investment			$ 106
Post-modification, Recorded Investment			$ 106
Other [Member] | Automobile [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	46	42	78
Pre-modification, Recorded Investment	$ 150	$ 255	$ 339
Post-modification, Recorded Investment	$ 150	$ 255	$ 339
Other [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	13	1	2
Pre-modification, Recorded Investment	$ 116	$ 45	$ 14
Post-modification, Recorded Investment	$ 116	$ 45	$ 14
Combination of Concession Types [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	6	7	9
Pre-modification, Recorded Investment	$ 3,238	$ 1,152	$ 2,649
Post-modification, Recorded Investment	3,242	1,198	3,040
Financial Effects of Modification, Recorded Investment	4	46	391
Financial Effects of Modification, Interest	$ (159)	$ (264)	$ (250)
Combination of Concession Types [Member] | Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	9	7	11
Pre-modification, Recorded Investment	$ 32,444	$ 19,167	$ 6,229
Post-modification, Recorded Investment	31,439	19,030	5,578
Financial Effects of Modification, Recorded Investment	(1,005)	(137)	(651)
Financial Effects of Modification, Interest	$ (245)	$ (20)	$ (458)
Combination of Concession Types [Member] | Residential Builder and Developer [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification			3
Pre-modification, Recorded Investment			$ 15,580
Post-modification, Recorded Investment			15,514
Financial Effects of Modification, Recorded Investment			(66)
Financial Effects of Modification, Interest			$ (535)
Combination of Concession Types [Member] | Other Commercial Construction [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	2
Pre-modification, Recorded Investment	$ 10,375
Post-modification, Recorded Investment	10,375
Financial Effects of Modification, Interest	$ (49)
Combination of Concession Types [Member] | Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	26	30	61
Pre-modification, Recorded Investment	$ 4,024	$ 4,211	$ 73,940
Post-modification, Recorded Investment	4,277	4,287	70,854
Financial Effects of Modification, Recorded Investment	253	76	(3,086)
Financial Effects of Modification, Interest	$ (483)	$ (483)	$ (924)
Combination of Concession Types [Member] | Residential Limited Documentation [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	9	21	19
Pre-modification, Recorded Investment	$ 1,536	$ 3,806	$ 2,826
Post-modification, Recorded Investment	1,635	3,846	3,148
Financial Effects of Modification, Recorded Investment	99	40	322
Financial Effects of Modification, Interest	$ (121)	$ (386)	$ (790)
Combination of Concession Types [Member] | Home Equity Lines and Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	63	47	28
Pre-modification, Recorded Investment	$ 5,203	$ 5,031	$ 2,190
Post-modification, Recorded Investment	5,204	5,031	2,190
Financial Effects of Modification, Recorded Investment	1
Financial Effects of Modification, Interest	$ (677)	$ (560)	$ (270)
Combination of Concession Types [Member] | Automobile [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	57	81	225
Pre-modification, Recorded Investment	$ 948	$ 1,189	$ 2,552
Post-modification, Recorded Investment	948	1,189	2,552
Financial Effects of Modification, Interest	$ (43)	$ (100)	$ (191)
Combination of Concession Types [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	40	70	120
Pre-modification, Recorded Investment	$ 396	$ 2,502	$ 4,248
Post-modification, Recorded Investment	396	2,502	4,248
Financial Effects of Modification, Interest	$ (45)	$ (761)	$ (1,187)
Interest Rate Reduction [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification		1
Pre-modification, Recorded Investment		$ 255
Post-modification, Recorded Investment		252
Financial Effects of Modification, Recorded Investment		(3)
Financial Effects of Modification, Interest		$ (48)
Interest Rate Reduction [Member] | Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	1		1
Pre-modification, Recorded Investment	$ 99		$ 104
Post-modification, Recorded Investment	99		335
Financial Effects of Modification, Recorded Investment			231
Financial Effects of Modification, Interest	$ (19)		$ (54)
Interest Rate Reduction [Member] | Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification		11
Pre-modification, Recorded Investment		$ 1,146
Post-modification, Recorded Investment		1,222
Financial Effects of Modification, Recorded Investment		76
Financial Effects of Modification, Interest		$ (152)
Interest Rate Reduction [Member] | Home Equity Lines and Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification		6	1
Pre-modification, Recorded Investment		$ 535	$ 99
Post-modification, Recorded Investment		535	99
Financial Effects of Modification, Interest		$ (120)	$ (8)
Interest Rate Reduction [Member] | Automobile [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	7	9	15
Pre-modification, Recorded Investment	$ 137	$ 152	$ 235
Post-modification, Recorded Investment	137	152	235
Financial Effects of Modification, Interest	$ (10)	$ (12)	$ (22)
Interest Rate Reduction [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification		4	1
Pre-modification, Recorded Investment		$ 293	$ 12
Post-modification, Recorded Investment		293	12
Financial Effects of Modification, Interest		$ (63)	$ (2)