Fair Value Measurement - Summary of Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Assets [Abstract]
Available for sale securities	$ 72,557	$ 71,884
Obligations of U.S. Government Corporations and Agencies [Member]
Assets [Abstract]
Available for sale securities	58,247	56,409
Obligations of States and Political Subdivisions [Member]
Assets [Abstract]
Available for sale securities	14,310	14,580
Corporate Bonds [Member]
Assets [Abstract]
Available for sale securities		895
Fair Value on a Recurring Basis [Member]
Liabilities [Abstract]
Interest rate swaps	316	38
Total liabilities at fair value	316	38
Assets [Abstract]
Available for sale securities	72,557	71,884
Mutual funds	403	382
Interest rate swaps		367
Total assets at fair value	72,960	72,633
Fair Value on a Recurring Basis [Member] \| Obligations of U.S. Government Corporations and Agencies [Member]
Assets [Abstract]
Available for sale securities	58,247	56,409
Fair Value on a Recurring Basis [Member] \| Obligations of States and Political Subdivisions [Member]
Assets [Abstract]
Available for sale securities	14,310	14,580
Fair Value on a Recurring Basis [Member] \| Corporate Bonds [Member]
Assets [Abstract]
Available for sale securities		895
Level 1 [Member]
Liabilities [Abstract]
Interest rate swaps	0	0
Total liabilities at fair value	0	0
Assets [Abstract]
Available for sale securities	0	0
Mutual funds	403	382
Interest rate swaps		0
Total assets at fair value	60,967	67,492
Level 1 [Member] \| Fair Value on a Recurring Basis [Member]
Liabilities [Abstract]
Interest rate swaps	0	0
Total liabilities at fair value	0	0
Assets [Abstract]
Available for sale securities	0	0
Mutual funds	403	382
Interest rate swaps		0
Total assets at fair value	403	382
Level 1 [Member] \| Fair Value on a Recurring Basis [Member] \| Obligations of U.S. Government Corporations and Agencies [Member]
Assets [Abstract]
Available for sale securities	0	0
Level 1 [Member] \| Fair Value on a Recurring Basis [Member] \| Obligations of States and Political Subdivisions [Member]
Assets [Abstract]
Available for sale securities	0	0
Level 1 [Member] \| Fair Value on a Recurring Basis [Member] \| Corporate Bonds [Member]
Assets [Abstract]
Available for sale securities		0
Level 2 [Member]
Liabilities [Abstract]
Interest rate swaps	316	38
Total liabilities at fair value	649,770	663,302
Assets [Abstract]
Available for sale securities	72,557	71,884
Mutual funds	0	0
Interest rate swaps		367
Total assets at fair value	92,427	90,028
Level 2 [Member] \| Fair Value on a Recurring Basis [Member]
Liabilities [Abstract]
Interest rate swaps	316	38
Total liabilities at fair value	316	38
Assets [Abstract]
Available for sale securities	72,557	71,884
Mutual funds	0	0
Interest rate swaps		367
Total assets at fair value	72,557	72,251
Level 2 [Member] \| Fair Value on a Recurring Basis [Member] \| Obligations of U.S. Government Corporations and Agencies [Member]
Assets [Abstract]
Available for sale securities	58,247	56,409
Level 2 [Member] \| Fair Value on a Recurring Basis [Member] \| Obligations of States and Political Subdivisions [Member]
Assets [Abstract]
Available for sale securities	14,310	14,580
Level 2 [Member] \| Fair Value on a Recurring Basis [Member] \| Corporate Bonds [Member]
Assets [Abstract]
Available for sale securities		895
Level 3 [Member]
Liabilities [Abstract]
Interest rate swaps	0	0
Total liabilities at fair value	0	0
Assets [Abstract]
Available for sale securities	0	0
Mutual funds	0	0
Interest rate swaps		0
Total assets at fair value	537,655	537,072
Level 3 [Member] \| Fair Value on a Recurring Basis [Member]
Liabilities [Abstract]
Interest rate swaps	0	0
Total liabilities at fair value	0	0
Assets [Abstract]
Available for sale securities	0	0
Mutual funds	0	0
Interest rate swaps		0
Total assets at fair value	0	0
Level 3 [Member] \| Fair Value on a Recurring Basis [Member] \| Obligations of U.S. Government Corporations and Agencies [Member]
Assets [Abstract]
Available for sale securities	0	0
Level 3 [Member] \| Fair Value on a Recurring Basis [Member] \| Obligations of States and Political Subdivisions [Member]
Assets [Abstract]
Available for sale securities	$ 0	0
Level 3 [Member] \| Fair Value on a Recurring Basis [Member] \| Corporate Bonds [Member]
Assets [Abstract]
Available for sale securities		$ 0

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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Fair value of financial obligations, including, but not limited to, debt instruments, derivative liabilities, federal funds purchased and sold under agreements to repurchase, securities loaned or sold under agreements to repurchase, financial instruments sold not yet purchased, guarantees, line of credit, loans and notes payable, servicing liability, and trading liabilities.

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Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

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