Loans and Leases - Schedule of Subsequently Defaulted TDRs (Detail) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018 USD ($) SecurityLoan	Jun. 30, 2017 USD ($) SecurityLoan	Jun. 30, 2018 USD ($) SecurityLoan	Jun. 30, 2017 USD ($) SecurityLoan
Accounts, Notes, Loans and Financing Receivable
Threshold period for loans in default (in days)			30 days
Non-Covered TDRs \| TDRs Occurring during the Period
Accounts, Notes, Loans and Financing Receivable
Number of Loans \| SecurityLoan	87	124	145	206
Pre-modification Outstanding Recorded Investment	$ 27,761	$ 18,453	$ 58,105	$ 29,206
Post-modification Outstanding Recorded Investment	$ 20,108	$ 17,892	$ 46,691	$ 28,398
Number of loans \| SecurityLoan	61	81	126	168
Recorded investment	$ 5,482	$ 18,671	$ 22,694	$ 22,744
Non-Covered TDRs \| Commercial Loans \| Commercial real estate - Construction \| TDRs Occurring during the Period
Accounts, Notes, Loans and Financing Receivable
Number of Loans \| SecurityLoan	0	1	1	1
Pre-modification Outstanding Recorded Investment	$ 0	$ 275	$ 1,950	$ 275
Post-modification Outstanding Recorded Investment	$ 0	$ 275	$ 1,013	$ 275
Number of loans \| SecurityLoan	0	0	0	2
Recorded investment	$ 0	$ 0	$ 0	$ 132
Non-Covered TDRs \| Commercial Loans \| Commercial real estate - owner-occupied \| TDRs Occurring during the Period
Accounts, Notes, Loans and Financing Receivable
Number of Loans \| SecurityLoan	5	1	7	2
Pre-modification Outstanding Recorded Investment	$ 2,230	$ 32	$ 12,921	$ 1,730
Post-modification Outstanding Recorded Investment	$ 2,201	$ 31	$ 11,290	$ 1,698
Number of loans \| SecurityLoan	5	5	6	7
Recorded investment	$ 461	$ 2,297	$ 9,455	$ 2,404
Non-Covered TDRs \| Commercial Loans \| Commercial real estate - non-owner-occupied \| TDRs Occurring during the Period
Accounts, Notes, Loans and Financing Receivable
Number of Loans \| SecurityLoan	5	6	14	11
Pre-modification Outstanding Recorded Investment	$ 823	$ 2,721	$ 1,912	$ 4,409
Post-modification Outstanding Recorded Investment	$ 780	$ 2,795	$ 1,854	$ 4,465
Number of loans \| SecurityLoan	9	9	15	14
Recorded investment	$ 1,448	$ 5,640	$ 1,813	$ 6,406
Non-Covered TDRs \| Commercial Loans \| Commercial and industrial \| TDRs Occurring during the Period
Accounts, Notes, Loans and Financing Receivable
Number of Loans \| SecurityLoan	16	24	32	33
Pre-modification Outstanding Recorded Investment	$ 21,103	$ 9,028	$ 35,338	$ 9,254
Post-modification Outstanding Recorded Investment	$ 13,618	$ 8,551	$ 26,684	$ 8,747
Number of loans \| SecurityLoan	8	17	21	25
Recorded investment	$ 1,437	$ 8,081	$ 7,100	$ 8,239
Non-Covered TDRs \| Residential Mortgage \| Residential mortgage \| TDRs Occurring during the Period
Accounts, Notes, Loans and Financing Receivable
Number of Loans \| SecurityLoan	7	6	7	10
Pre-modification Outstanding Recorded Investment	$ 688	$ 521	$ 688	$ 780
Post-modification Outstanding Recorded Investment	$ 633	$ 492	$ 633	$ 730
Number of loans \| SecurityLoan	7	5	10	21
Recorded investment	$ 775	$ 454	$ 1,081	$ 1,854
Non-Covered TDRs \| Consumer and Other Loans \| Consumer - Home equity \| TDRs Occurring during the Period
Accounts, Notes, Loans and Financing Receivable
Number of Loans \| SecurityLoan	19	33	33	66
Pre-modification Outstanding Recorded Investment	$ 2,361	$ 4,820	$ 4,170	$ 10,851
Post-modification Outstanding Recorded Investment	$ 2,350	$ 4,807	$ 4,133	$ 10,771
Number of loans \| SecurityLoan	11	19	26	37
Recorded investment	$ 1,129	$ 1,532	$ 2,242	$ 2,488
Non-Covered TDRs \| Consumer and Other Loans \| Consumer - Other \| TDRs Occurring during the Period
Accounts, Notes, Loans and Financing Receivable
Number of Loans \| SecurityLoan	35	53	51	83
Pre-modification Outstanding Recorded Investment	$ 556	$ 1,056	$ 1,126	$ 1,907
Post-modification Outstanding Recorded Investment	$ 526	$ 941	$ 1,084	$ 1,712
Number of loans \| SecurityLoan	21	26	48	62
Recorded investment	$ 232	$ 667	$ 1,003	$ 1,221

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Number of financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953676-111524

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953682-111524

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