Past Due Loans, Allowance For Credit Losses, Impaired Loans, and TDRS - TDRs By Class (Details) - USD ($)		6 Months Ended	12 Months Ended
		Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - TDRs By Class [Line Items]
Accruing TDRs		$ 1,441,000	$ 1,866,000
Non-accrual	[1]	7,841,000	6,612,000
Total		9,282,000	8,478,000	$ 9,998,000
Specific reserves related to TDRs		670,000	0
Commercial and industrial | Commercial and industrial
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - TDRs By Class [Line Items]
Accruing TDRs		236,000	246,000
Non-accrual	[1]	6,928,000	5,994,000
Total		7,164,000	6,240,000
Commercial and industrial | Agricultural
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - TDRs By Class [Line Items]
Accruing TDRs		0	0
Non-accrual	[1]	0	0
Total		0	0
Commercial real estate
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - TDRs By Class [Line Items]
Accruing TDRs		343,000	738,000
Non-accrual	[1]	383,000	0
Total		726,000	738,000
Commercial real estate | Office, retail, and industrial
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - TDRs By Class [Line Items]
Accruing TDRs		0	0
Non-accrual	[1]	383,000	0
Total		383,000	0
Commercial real estate | Multi-family
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - TDRs By Class [Line Items]
Accruing TDRs		167,000	557,000
Non-accrual	[1]	0	0
Total		167,000	557,000
Commercial real estate | Construction
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - TDRs By Class [Line Items]
Accruing TDRs		0	0
Non-accrual	[1]	0	0
Total		0	0
Commercial real estate | Other commercial real estate
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - TDRs By Class [Line Items]
Accruing TDRs		176,000	181,000
Non-accrual	[1]	0	0
Total		176,000	181,000
Total corporate loans
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - TDRs By Class [Line Items]
Accruing TDRs		579,000	984,000
Non-accrual	[1]	7,311,000	5,994,000
Total		7,890,000	6,978,000
Consumer loans
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - TDRs By Class [Line Items]
Accruing TDRs		862,000	882,000
Non-accrual	[1]	530,000	618,000
Total		1,392,000	1,500,000
Consumer loans | Home equity
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - TDRs By Class [Line Items]
Accruing TDRs		109,000	113,000
Non-accrual	[1]	257,000	327,000
Total		366,000	440,000
Consumer loans | 1-4 family mortgages
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - TDRs By Class [Line Items]
Accruing TDRs		753,000	769,000
Non-accrual	[1]	273,000	291,000
Total		1,026,000	1,060,000
Consumer loans | Installment
Past Due Loans, Allowance For Credit Losses, and Impaired Loans (Details) - TDRs By Class [Line Items]
Accruing TDRs		0	0
Non-accrual	[1]	0	0
Total		$ 0	$ 0

[1] These TDRs are included in non-accrual loans in the preceding tables.