Loans and Leases - Schedule of Modified TDRs (Detail) - TDRs Occurring during the Period - TDRs $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019 USD ($) SecurityLoan	Sep. 30, 2018 USD ($) SecurityLoan	Sep. 30, 2019 USD ($) SecurityLoan	Sep. 30, 2018 USD ($) SecurityLoan
Financing Receivable, Modifications
Number of Loans \| SecurityLoan	74	45	236	163
Pre-modification Outstanding Recorded Investment	$ 28,561	$ 6,720	$ 71,162	$ 59,322
Recorded investment	$ 4,111	$ 1,529	$ 17,084	$ 18,195
Number of loans \| SecurityLoan	17	14	124	88
Extended maturities	$ 2,476	$ 3,658	$ 13,097	$ 10,020
Maturity and interest rate adjustment	288	267	715	368
Movement to or extension of interest-rate only payments	48	0	1,827	48
Interest rate adjustment	0	0	71	101
Financing Receivable Modifications Forbearance	22,202	802	25,068	14,386
Other concession(s)	3,724	1,810	20,250	21,031
TDRs during period	$ 28,738	$ 6,537	$ 61,028	$ 45,954
Commercial Loans \| Real estate - construction
Financing Receivable, Modifications
Number of Loans \| SecurityLoan	1	0	1	1
Pre-modification Outstanding Recorded Investment	$ 6,331	$ 0	$ 6,331	$ 1,950
TDRs during period	$ 7,602	$ 0	$ 7,602	$ 976
Commercial Loans \| Real estate - owner-occupied
Financing Receivable, Modifications
Number of Loans \| SecurityLoan	7	1	11	8
Pre-modification Outstanding Recorded Investment	$ 8,936	$ 2,312	$ 10,153	$ 15,233
Recorded investment	$ 0	$ 929	$ 1,225	$ 10,101
Number of loans \| SecurityLoan	0	1	6	6
TDRs during period	$ 8,691	$ 2,312	$ 9,869	$ 13,373
Commercial Loans \| Real estate - non-owner-occupied
Financing Receivable, Modifications
Number of Loans \| SecurityLoan	6	6	16	13
Pre-modification Outstanding Recorded Investment	$ 1,553	$ 1,818	$ 7,931	$ 3,228
Recorded investment	$ 2,460	$ 7	$ 5,176	$ 1,084
Number of loans \| SecurityLoan	2	1	16	6
TDRs during period	$ 1,210	$ 1,790	$ 7,233	$ 3,064
Commercial Loans \| Commercial and industrial
Financing Receivable, Modifications
Number of Loans \| SecurityLoan	14	9	48	32
Pre-modification Outstanding Recorded Investment	$ 1,954	$ 829	$ 29,156	$ 32,827
Recorded investment	$ 1,429	$ 127	$ 6,859	$ 3,632
Number of loans \| SecurityLoan	8	2	25	12
TDRs during period	$ 1,952	$ 804	$ 19,594	$ 22,769
Residential mortgage loans \| Residential mortgage
Financing Receivable, Modifications
Number of Loans \| SecurityLoan	10	3	28	9
Pre-modification Outstanding Recorded Investment	$ 7,210	$ 257	$ 8,897	$ 898
Recorded investment	$ 101	$ 0	$ 1,394	$ 912
Number of loans \| SecurityLoan	1	0	18	8
TDRs during period	$ 6,870	$ 255	$ 8,524	$ 837
Consumer and Other Loans \| Consumer - Home equity
Financing Receivable, Modifications
Number of Loans \| SecurityLoan	19	15	69	47
Pre-modification Outstanding Recorded Investment	$ 2,375	$ 1,152	$ 7,629	$ 4,130
Recorded investment	$ 64	$ 380	$ 1,873	$ 1,978
Number of loans \| SecurityLoan	1	4	21	17
TDRs during period	$ 2,237	$ 1,124	$ 7,268	$ 4,047
Consumer and Other Loans \| Consumer - Other
Financing Receivable, Modifications
Number of Loans \| SecurityLoan	17	11	63	53
Pre-modification Outstanding Recorded Investment	$ 202	$ 352	$ 1,065	$ 1,056
Recorded investment	$ 57	$ 86	$ 557	$ 488
Number of loans \| SecurityLoan	5	6	38	39
TDRs during period	$ 176	$ 252	$ 938	$ 888

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953676-111524

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
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-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953682-111524

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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-Paragraph 34
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