Loans and Leases - Loan Modification Activities that were Considered Troubled Debt Restructurings (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) Modification	Dec. 31, 2015 USD ($) Modification	Dec. 31, 2014 USD ($) Modification
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	739	817	760
Pre-modification, Recorded Investment	$ 279,696	$ 204,800	$ 134,351
Post-modification, Recorded Investment	268,415	198,405	130,190
Financial Effects of Modification, Recorded Investment	(11,281)	(6,395)	(4,161)
Financial Effects of Modification, Interest	$ (2,482)	$ (1,851)	$ (2,969)
Principal Deferral [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	56	49	39
Pre-modification, Recorded Investment	$ 24,323	$ 49,486	$ 19,077
Post-modification, Recorded Investment	23,558	48,388	18,997
Financial Effects of Modification, Recorded Investment	$ (765)	$ (1,098)	$ (80)
Principal Deferral [Member] | Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	127	114	95
Pre-modification, Recorded Investment	$ 102,872	$ 55,621	$ 29,035
Post-modification, Recorded Investment	102,446	50,807	23,628
Financial Effects of Modification, Recorded Investment	$ (426)	$ (4,814)	$ (5,407)
Principal Deferral [Member] | Residential Builder and Developer [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	3	2	2
Pre-modification, Recorded Investment	$ 23,905	$ 10,650	$ 1,639
Post-modification, Recorded Investment	22,958	10,598	$ 1,639
Financial Effects of Modification, Recorded Investment	$ (947)	$ (52)
Principal Deferral [Member] | Other Commercial Construction [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	1	4	4
Pre-modification, Recorded Investment	$ 250	$ 368	$ 6,703
Post-modification, Recorded Investment	$ 250	460	6,611
Financial Effects of Modification, Recorded Investment		$ 92	$ (92)
Principal Deferral [Member] | Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	73	58	28
Pre-modification, Recorded Investment	$ 11,082	$ 6,194	$ 2,710
Post-modification, Recorded Investment	11,771	6,528	2,905
Financial Effects of Modification, Recorded Investment	$ 689	$ 334	$ 195
Principal Deferral [Member] | Residential Limited Documentation [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	8	2	6
Pre-modification, Recorded Investment	$ 902	$ 426	$ 880
Post-modification, Recorded Investment	1,047	437	963
Financial Effects of Modification, Recorded Investment	$ 145	$ 11	$ 83
Principal Deferral [Member] | Home Equity Lines and Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	10	8	3
Pre-modification, Recorded Investment	$ 760	$ 2,175	$ 280
Post-modification, Recorded Investment	761	$ 2,175	$ 280
Financial Effects of Modification, Recorded Investment	$ 1
Principal Deferral [Member] | Automobile [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	117	192	208
Pre-modification, Recorded Investment	$ 1,124	$ 1,818	$ 3,293
Post-modification, Recorded Investment	$ 1,124	$ 1,818	$ 3,293
Principal Deferral [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	57	102	33
Pre-modification, Recorded Investment	$ 968	$ 1,995	$ 245
Post-modification, Recorded Investment	$ 968	$ 1,995	$ 245
Combination of Concession Types [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	23	6	7
Pre-modification, Recorded Investment	$ 15,695	$ 3,238	$ 1,152
Post-modification, Recorded Investment	15,603	3,242	1,198
Financial Effects of Modification, Recorded Investment	(92)	4	46
Financial Effects of Modification, Interest	$ (585)	$ (159)	$ (264)
Combination of Concession Types [Member] | Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	37	9	7
Pre-modification, Recorded Investment	$ 51,221	$ 32,444	$ 19,167
Post-modification, Recorded Investment	41,673	31,439	19,030
Financial Effects of Modification, Recorded Investment	(9,548)	(1,005)	(137)
Financial Effects of Modification, Interest	$ (95)	$ (245)	$ (20)
Combination of Concession Types [Member] | Residential Builder and Developer [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	3
Pre-modification, Recorded Investment	$ 15,755
Post-modification, Recorded Investment	15,123
Financial Effects of Modification, Recorded Investment	$ (632)
Combination of Concession Types [Member] | Other Commercial Construction [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	2	2
Pre-modification, Recorded Investment	$ 2,863	$ 10,375
Post-modification, Recorded Investment	2,782	10,375
Financial Effects of Modification, Recorded Investment	$ (81)
Financial Effects of Modification, Interest		$ (49)
Combination of Concession Types [Member] | Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	46	26	30
Pre-modification, Recorded Investment	$ 8,975	$ 4,024	$ 4,211
Post-modification, Recorded Investment	9,367	4,277	4,287
Financial Effects of Modification, Recorded Investment	392	253	76
Financial Effects of Modification, Interest	$ (120)	$ (483)	$ (483)
Combination of Concession Types [Member] | Residential Limited Documentation [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	13	9	21
Pre-modification, Recorded Investment	$ 2,658	$ 1,536	$ 3,806
Post-modification, Recorded Investment	2,917	1,635	3,846
Financial Effects of Modification, Recorded Investment	259	99	40
Financial Effects of Modification, Interest	$ (706)	$ (121)	$ (386)
Combination of Concession Types [Member] | Home Equity Lines and Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	93	63	47
Pre-modification, Recorded Investment	$ 11,110	$ 5,203	$ 5,031
Post-modification, Recorded Investment	11,110	5,204	5,031
Financial Effects of Modification, Recorded Investment		1
Financial Effects of Modification, Interest	$ (916)	$ (677)	$ (560)
Combination of Concession Types [Member] | Automobile [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	8	57	81
Pre-modification, Recorded Investment	$ 85	$ 948	$ 1,189
Post-modification, Recorded Investment	85	948	1,189
Financial Effects of Modification, Interest	$ (3)	$ (43)	$ (100)
Combination of Concession Types [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	17	40	70
Pre-modification, Recorded Investment	$ 196	$ 396	$ 2,502
Post-modification, Recorded Investment	196	396	2,502
Financial Effects of Modification, Interest	$ (32)	$ (45)	$ (761)
Interest Rate Reduction [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	1		1
Pre-modification, Recorded Investment	$ 129		$ 255
Post-modification, Recorded Investment	129		252
Financial Effects of Modification, Recorded Investment			(3)
Financial Effects of Modification, Interest	$ (25)		$ (48)
Interest Rate Reduction [Member] | Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification		1
Pre-modification, Recorded Investment		$ 99
Post-modification, Recorded Investment		99
Financial Effects of Modification, Interest		$ (19)
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
Pre-modification, Recorded Investment			$ 535
Post-modification, Recorded Investment			535
Financial Effects of Modification, Interest			$ (120)
Interest Rate Reduction [Member] | Automobile [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification		7	9
Pre-modification, Recorded Investment		$ 137	$ 152
Post-modification, Recorded Investment		137	152
Financial Effects of Modification, Interest		$ (10)	$ (12)
Interest Rate Reduction [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification			4
Pre-modification, Recorded Investment			$ 293
Post-modification, Recorded Investment			293
Financial Effects of Modification, Interest			$ (63)
Other [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	1	3	1
Pre-modification, Recorded Investment	$ 4,723	$ 4,169	$ 650
Post-modification, Recorded Investment	4,447	4,087
Financial Effects of Modification, Recorded Investment	$ (276)	$ (82)	$ (650)
Other [Member] | Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification		3	3
Pre-modification, Recorded Investment		$ 12,965	$ 29,912
Post-modification, Recorded Investment		12,827	31,604
Financial Effects of Modification, Recorded Investment		$ (138)	$ 1,692
Other [Member] | Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification		1	1
Pre-modification, Recorded Investment		$ 267	$ 188
Post-modification, Recorded Investment		$ 267	$ 188
Other [Member] | Automobile [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	38	46	42
Pre-modification, Recorded Investment	$ 55	$ 150	$ 255
Post-modification, Recorded Investment	$ 55	$ 150	$ 255
Other [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	5	13	1
Pre-modification, Recorded Investment	$ 45	$ 116	$ 45
Post-modification, Recorded Investment	$ 45	$ 116	$ 45