Fair Values of Assets and Liabilities - Carrying Amounts and Fair Values of Financial Instruments (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021
Carrying Amount [Member]
Fair Value Measurements Of Financial Instruments [Line Items]
Cash and due from banks	$ 120,289	$ 84,738
Interest-bearing deposits	404,516	310,634
Available-for-sale Securities, Current	933,204	1,041,380
Debt Securities, Held-to-maturity	512,911	541,311
Other investments	13,142	12,838
Loans Held for sale, Amount	10,506	18,583
Loans and Leases Receivable, Net of Deferred Income	6,952,112	6,839,230
Deposits	8,171,847	7,982,498
Short-term borrowings	95,748	138,315
Subordinated debt	170,815	170,775
Long-term debt	5,398	5,573
Capital Lease Obligations, Current	5,799	5,921
Estimate of Fair Value Measurement [Member]
Fair Value Measurements Of Financial Instruments [Line Items]
Cash and due from banks	120,289	84,738
Interest-bearing deposits	404,516	310,634
Available-for-sale Securities, Current	933,204	1,041,380
Debt Securities, Held-to-maturity	477,088	536,651
Other investments	13,142	12,838
Loans Held for sale, Amount	10,506	18,583
Loans and Leases Receivable, Net of Deferred Income	7,154,726	7,169,768
Deposits	8,164,467	7,980,101
Short-term borrowings	93,203	136,473
Subordinated debt	168,231	175,040
Long-term debt	5,587	6,065
Capital Lease Obligations, Current	5,799	5,921
Estimate of Fair Value Measurement [Member] | Level 1 [Member]
Fair Value Measurements Of Financial Instruments [Line Items]
Cash and due from banks	120,289	84,738
Interest-bearing deposits	404,516	310,634
Available-for-sale Securities, Current	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, Current	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
Available-for-sale Securities, Current	933,204	1,041,380
Debt Securities, Held-to-maturity	477,088	536,651
Other investments	11,972	11,668
Loans Held for sale, Amount	10,506	18,583
Loans and Leases Receivable, Net of Deferred Income	25,306	42,538
Deposits	8,164,467	7,980,101
Short-term borrowings	93,203	136,473
Subordinated debt	0	0
Long-term debt	5,587	6,065
Capital Lease Obligations, Current	5,799	5,921
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
Available-for-sale Securities, Current	0	0
Debt Securities, Held-to-maturity	0	0
Other investments	1,170	1,170
Loans Held for sale, Amount	0	0
Loans and Leases Receivable, Net of Deferred Income	7,129,420	7,127,230
Deposits	0	0
Short-term borrowings	0	0
Subordinated debt	168,231	175,040
Long-term debt	0	0
Capital Lease Obligations, Current	0	0
Cash and due from banks	120,289	84,738
Interest-bearing deposits	404,516	310,634
Available-for-sale Securities, Current	933,204	1,041,380
Securities available for sale, at fair value	933,204	1,041,380
Debt Securities, Held-to-maturity	512,911	541,311
Other investments	13,142	12,838
Loans and Leases Receivable, Net of Deferred Income	6,952,112	6,839,230	$ 6,736,894
Deposits	8,171,847	7,982,498
Short-term borrowings	95,748	138,315
Subordinated debt	170,815	170,775
Long-term debt	5,398	5,573
Level 1 [Member]
Fair Value Measurements Of Financial Instruments [Line Items]
Available-for-sale Securities, Current	0	0
Other investments	0	0
Level 2 [Member]
Fair Value Measurements Of Financial Instruments [Line Items]
Available-for-sale Securities, Current	933,204	1,041,380
Other investments	11,972	11,668
Level 3 [Member]
Fair Value Measurements Of Financial Instruments [Line Items]
Available-for-sale Securities, Current	0	0
Other investments	$ 1,170	$ 1,170