Fair Value Measurement, Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Assets [Abstract]
Available for sale securities	$ 72,629	$ 72,153
Fair Value on a Recurring Basis [Member]
Assets [Abstract]
Available for sale securities	72,629	72,153
Interest rate swaps	594	233
Total assets at fair value	73,223	72,386
Liabilities [Abstract]
Interest rate swaps	22	119
Total liabilities at fair value	22	119
Fair Value on a Recurring Basis [Member] \| Obligations of U.S. Government Corporations and Agencies [Member]
Assets [Abstract]
Available for sale securities	57,396	52,377
Fair Value on a Recurring Basis [Member] \| Obligations of States and Political Subdivisions [Member]
Assets [Abstract]
Available for sale securities	14,383	15,255
Fair Value on a Recurring Basis [Member] \| Corporate Bonds [Member]
Assets [Abstract]
Available for sale securities	850	4,139
Fair Value on a Recurring Basis [Member] \| Mutual Funds [Member]
Assets [Abstract]
Available for sale securities		382
Level 1 [Member]
Assets [Abstract]
Available for sale securities	0	382
Interest rate swaps	0	0
Total assets at fair value	20,989	29,473
Liabilities [Abstract]
Interest rate swaps	0	0
Total liabilities at fair value	0	0
Level 1 [Member] \| Fair Value on a Recurring Basis [Member]
Assets [Abstract]
Available for sale securities	0	382
Interest rate swaps	0	0
Total assets at fair value	0	382
Liabilities [Abstract]
Interest rate swaps	0	0
Total liabilities at fair value	0	0
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	0
Level 1 [Member] \| Fair Value on a Recurring Basis [Member] \| Mutual Funds [Member]
Assets [Abstract]
Available for sale securities		382
Level 2 [Member]
Assets [Abstract]
Available for sale securities	72,629	71,771
Interest rate swaps	594	233
Total assets at fair value	91,167	582,867
Liabilities [Abstract]
Interest rate swaps	22	119
Total liabilities at fair value	604,820	581,426
Level 2 [Member] \| Fair Value on a Recurring Basis [Member]
Assets [Abstract]
Available for sale securities	72,629	71,771
Interest rate swaps	594	233
Total assets at fair value	73,223	72,004
Liabilities [Abstract]
Interest rate swaps	22	119
Total liabilities at fair value	22	119
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	57,396	52,377
Level 2 [Member] \| Fair Value on a Recurring Basis [Member] \| Obligations of States and Political Subdivisions [Member]
Assets [Abstract]
Available for sale securities	14,383	15,255
Level 2 [Member] \| Fair Value on a Recurring Basis [Member] \| Corporate Bonds [Member]
Assets [Abstract]
Available for sale securities	850	4,139
Level 2 [Member] \| Fair Value on a Recurring Basis [Member] \| Mutual Funds [Member]
Assets [Abstract]
Available for sale securities		0
Level 3 [Member]
Assets [Abstract]
Available for sale securities	0	0
Interest rate swaps	0	0
Total assets at fair value	509,568	46
Liabilities [Abstract]
Interest rate swaps	0	0
Total liabilities at fair value	0	0
Level 3 [Member] \| Fair Value on a Recurring Basis [Member]
Assets [Abstract]
Available for sale securities	0	0
Interest rate swaps	0	0
Total assets at fair value	0	0
Liabilities [Abstract]
Interest rate swaps	0	0
Total liabilities 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	0
Level 3 [Member] \| Fair Value on a Recurring Basis [Member] \| Mutual Funds [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 and equity securities categorized neither as held-to-maturity nor trading.

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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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