Loans and Leases - Loan Modification Activities that were Considered Troubled Debt Restructurings (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) Modification	Dec. 31, 2017 USD ($) Modification	Dec. 31, 2016 USD ($) Modification
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	557	654	739
Pre-modification Recorded Investment	$ 175,583	$ 216,063	$ 279,696
Post- modification	$ 180,224	$ 191,522	$ 268,415
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	83	83	81
Pre-modification Recorded Investment	$ 30,217	$ 44,924	$ 44,870
Post- modification	30,731	40,882	43,737
Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	90,639	62,302	164,883
Principal Deferral [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	16,870	17,039	23,558
Interest Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	978
Interest Rate Reduction [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	175
Other [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	10,896	7,818	4,676
Other [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	4,686	868	4,576
Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	77,711	121,402	98,856
Combination of Concession Types [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 9,000	$ 22,975	$ 15,603
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	203	217	164
Pre-modification Recorded Investment	$ 102,445	$ 111,036	$ 154,093
Post- modification	102,914	88,663	144,119
Commercial, Financial, Leasing, etc. [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	50,490	25,051	102,446
Commercial, Financial, Leasing, etc. [Member] | Interest Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	803
Commercial, Financial, Leasing, etc. [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	6,210	6,459
Commercial, Financial, Leasing, etc. [Member] | Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 45,411	$ 57,153	$ 41,673
Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	134	141	119
Pre-modification Recorded Investment	$ 34,798	$ 31,827	$ 20,057
Post- modification	38,072	34,607	21,138
Residential [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	19,962	16,633	11,771
Residential [Member] | Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 18,110	$ 17,974	$ 9,367
Residential Limited Documentation [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	9	20	21
Pre-modification Recorded Investment	$ 1,887	$ 4,230	$ 3,560
Post- modification	2,250	4,572	3,964
Residential Limited Documentation [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	827	911	1,047
Residential Limited Documentation [Member] | Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 1,423	$ 3,661	$ 2,917
Home Equity Lines and Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	47	110	103
Pre-modification Recorded Investment	$ 3,952	$ 10,049	$ 11,870
Post- modification	3,979	10,213	11,871
Home Equity Lines and Loans [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	224	1,137	761
Home Equity Lines and Loans [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Post- modification		491
Home Equity Lines and Loans [Member] | Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 3,755	$ 8,585	$ 11,110
Automobile [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	73	69	163
Pre-modification Recorded Investment	$ 1,330	$ 1,378	$ 1,264
Post- modification	1,330	1,378	1,264
Automobile [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	1,318	1,203	1,124
Automobile [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Post- modification			55
Automobile [Member] | Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 12	$ 175	$ 85
Other [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification			69
Pre-modification Recorded Investment			$ 891
Post- modification			891
Other [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification			698
Other [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Post- modification			25
Other [Member] | Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification			$ 168
Residential Builder and Developer [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification		3	6
Pre-modification Recorded Investment		$ 12,291	$ 39,660
Post- modification		10,879	38,081
Residential Builder and Developer [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification			22,958
Residential Builder and Developer [Member] | Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification		$ 10,879	$ 15,123
Other Commercial Construction [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	1	2	3
Pre-modification Recorded Investment	$ 752	$ 168	$ 3,113
Post- modification	746	168	3,032
Other Commercial Construction [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 746	$ 168	250
Other Commercial Construction [Member] | Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification			$ 2,782
Recreational Finance [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	7	9	10
Pre-modification Recorded Investment	$ 202	$ 160	$ 318
Post- modification	202	160	318
Recreational Finance [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 202	$ 160	270
Recreational Finance [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Post- modification			20
Recreational Finance [Member] | Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification			$ 28