Fair Values of Assets and Liabilities - Carrying Amounts and Fair Values of Financial Instruments (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019
Fair Value Measurements Of Financial Instruments [Line Items]
Cash and due from banks	$ 97,060	$ 102,346
Interest-bearing deposits	283,037	19,510
Securities available for sale, at fair value	908,236	902,292
Debt Securities, Held-to-maturity	268,638	337,123
Other investments	12,966	16,761
Loans and Leases Receivable, Net of Deferred Income	6,949,716	6,189,148	$ 6,099,561
Deposits	7,703,907	6,677,615
Short-term borrowings	122,356	201,853
Subordinated debt	170,572	170,450
Long-term debt	56,424	56,917
Capital Lease Obligations	6,494	6,815
Level 1 [Member]
Fair Value Measurements Of Financial Instruments [Line Items]
Securities available for sale, at fair value	0	0
Other investments	0	0
Level 2 [Member]
Fair Value Measurements Of Financial Instruments [Line Items]
Securities available for sale, at fair value	908,236	902,292
Other investments	11,296	15,091
Level 3 [Member]
Fair Value Measurements Of Financial Instruments [Line Items]
Securities available for sale, at fair value	0	0
Other investments	1,670	1,670
Carrying Amount [Member]
Fair Value Measurements Of Financial Instruments [Line Items]
Cash and due from banks	97,060	102,346
Interest-bearing deposits	283,037	19,510
Securities available for sale, at fair value	908,236	902,292
Debt Securities, Held-to-maturity	268,638	337,123
Other investments	12,966	16,761
Loans Held for sale, Amount	37,998	15,989
Loans and Leases Receivable, Net of Deferred Income	6,949,716	6,189,148
Deposits	7,703,907	6,677,615
Short-term borrowings	122,356	201,853
Subordinated debt	170,572	170,450
Long-term debt	56,424	56,917
Capital Lease Obligations	6,494	6,815
Estimate of Fair Value Measurement [Member]
Fair Value Measurements Of Financial Instruments [Line Items]
Cash and due from banks	97,060	102,346
Interest-bearing deposits	283,037	19,510
Securities available for sale, at fair value	908,236	902,292
Debt Securities, Held-to-maturity	276,988	338,718
Other investments	12,966	16,761
Loans Held for sale, Amount	37,998	15,989
Loans and Leases Receivable, Net of Deferred Income	7,391,037	6,393,872
Deposits	7,707,618	6,677,595
Short-term borrowings	121,828	201,151
Subordinated debt	164,565	171,772
Long-term debt	58,372	58,051
Capital Lease Obligations	6,494	6,815
Estimate of Fair Value Measurement [Member] \| Level 1 [Member]
Fair Value Measurements Of Financial Instruments [Line Items]
Cash and due from banks	97,060	102,346
Interest-bearing deposits	283,037	19,510
Securities available for sale, at fair value	0	0
Debt Securities, Held-to-maturity	0	0
Other investments	0	0
Loans Held for sale, Amount	0	0
Loans and Leases Receivable, Net of Deferred Income	0	0
Deposits	0	0
Short-term borrowings	0	0
Subordinated debt	0	0
Long-term debt	0	0
Capital Lease Obligations	0	0
Estimate of Fair Value Measurement [Member] \| Level 2 [Member]
Fair Value Measurements Of Financial Instruments [Line Items]
Cash and due from banks	0	0
Interest-bearing deposits	0	0
Securities available for sale, at fair value	908,236	902,292
Debt Securities, Held-to-maturity	276,988	338,718
Other investments	11,296	15,091
Loans Held for sale, Amount	37,998	15,989
Loans and Leases Receivable, Net of Deferred Income	28,793	12,267
Deposits	7,707,618	6,677,595
Short-term borrowings	121,828	201,151
Subordinated debt	0	0
Long-term debt	58,372	58,051
Capital Lease Obligations	6,494	6,815
Estimate of Fair Value Measurement [Member] \| Level 3 [Member]
Fair Value Measurements Of Financial Instruments [Line Items]
Cash and due from banks	0	0
Interest-bearing deposits	0	0
Securities available for sale, at fair value	0	0
Debt Securities, Held-to-maturity	0	0
Other investments	1,670	1,670
Loans Held for sale, Amount	0	0
Loans and Leases Receivable, Net of Deferred Income	7,362,244	6,381,605
Deposits	0	0
Short-term borrowings	0	0
Subordinated debt	164,565	171,772
Long-term debt	0	0
Capital Lease Obligations	$ 0	$ 0

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal through the balance sheet date.

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For banks and other depository institutions: Includes cash on hand (currency and coin), cash items in process of collection, noninterest bearing deposits due from other financial institutions (including corporate credit unions), and noninterest bearing balances with the Federal Reserve Banks, Federal Home Loan Banks and central banks.

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The aggregate of all deposit liabilities held by the entity, including foreign and domestic, interest and noninterest bearing; may include demand deposits, saving deposits, Negotiable Order of Withdrawal (NOW) and time deposits among others.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of investment in debt security measured at amortized cost (held-to-maturity).

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For banks and other depository institutions (including Federal Reserve Banks, if applicable): Interest-bearing deposits in other financial institutions for relatively short periods of time including, for example, certificates of deposits, which are presented separately from cash on the balance sheet.

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Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

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Amount, before valuation allowance, of financing receivable classified as held-for-sale.

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Amount of investments classified as other.

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Amount of long-term debt classified as other.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of subordinated debt (with initial maturities beyond one year or beyond the operating cycle if longer). Subordinated debt places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets.

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