Loans and Leases Receivable and Allowance for Loan and Lease Losses - Narrative (Detail)	12 Months Ended
Dec. 31, 2019 USD ($) Loan Commitment Allowance	Dec. 31, 2018 USD ($) Loan Commitment	Dec. 31, 2017 USD ($) Commitment Loan Allowance
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans held for sale, average life from purchase to sale (days)	30 days
Troubled debt restructurings loans	$ 13,300,000	$ 19,200,000	$ 20,400,000
Minimum performance requirement (months)	6 months
Sustained performance period (months)	6 months
Lease receivables restructured as a TDR	$ 0	$ 0	$ 0
Number of loans \| Loan	28	41	40
Commitments to lend additional funds to debtors \| Commitment	0	0	0
Number of TDR loans that defaulted on payments \| Loan	4	4	5
Amount of TDR loans that defaulted on payments	$ 154,000	$ 92,000	$ 211,000
Allowance for TDR modification	$ 17,000		$ 1,000
TDR modification (allowance) \| Allowance	15		1
Troubled Debt Restructurings
Financing Receivable, Troubled Debt Restructuring [Line Items]
Sustained performance period (months)	9 months
Residential Real Estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Other real estate owned	$ 200,000	200,000
Foreclosure loans	900,000	$ 2,100,000
Commercial and industrial (including owner occupied commercial real estate)
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of TDR loans that defaulted on payments \| Loan		1	1
Amount of TDR loans that defaulted on payments		$ 1,500,000	$ 2,100,000
Federal Home Loan Bank of Pittsburgh
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans pledged as collateral	$ 4,600,000,000	$ 5,400,000,000
Principal Forgiveness
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of loans \| Loan	0	0	0

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Financing Receivable Impairment Modification Minimum Period

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Loans Held For Sale Average Life From Purchase To Sale

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Loans Receivables Gross Troubled Debt Restructurings

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Number Of Commitments To Lend Additional Funds For Troubled Debt Restructurings

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Specific Allowance, Loans Modified In Troubled Debt Restructurings

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The effect of a change in method or methods for calculating the allowance for credit losses on the current period provision.

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Amount of financing receivable modified as troubled debt restructuring within previous 12 months, with subsequent payment default.

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Carrying amount as of the balance sheet date of loans that have been pledged as collateral for borrowings. If the secured party has the right by contract or custom to sell or re-pledge the collateral, then the debtor reclassifies that asset and report that asset in its statement of financial position separately from other assets not so encumbered.

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Recorded investment of consumer mortgage loan receivables secured by residential real estate properties for which formal foreclosure proceedings are in process.

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Carrying amount of other real estate not separately disclosed, including, but not limited to, real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations may also be included in real estate owned. This does not include real estate assets taken in settlement of troubled loans through surrender or foreclosure.

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