Loans - Narrative (Details) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2019 USD ($) Contract	Dec. 31, 2018 USD ($) Contract	Jun. 30, 2018 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Period for order of valuations (at least)	18 months
Financing Receivable, Troubled Debt Restructuring	$ 4,061		$ 6,474
Number of troubled debt restructured loan paid off | Contract	1	1
Number of loans which has periodic late payments | Contract	1
Financing Receivable, Modifications, Subsequent Default, Number of Contracts with Active Forbearance Agreements	0
Consumer mortgage loans secured by residential real estate properties for which formal foreclosure proceedings are in process	$ 795	$ 661
Residential mortgage and commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Threshold period past due to discontinue accrual interest on financing receivable	90 days
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Threshold period past due for write-off of financing receivable (no later than)	120 days
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Period of financing receivable, updated valuation on real estate secured loans (number of days past due)	90 days
Number of previous months with no updated valuation completed for corporation to update valuation	12 months
Impaired financing receivable, valuation on real estate collateralized loans (number of days after the loan is classified as impaired)	30 days
Entity Loan Modification Program
Accounts, Notes, Loans and Financing Receivable [Line Items]
Proceeds from paid off troubled debt restructured loans	$ 2,198	$ 832
Maximum | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable term	20 years
Loan-to-value ratio (no greater than)	80.00%
Maximum | Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable term	30 years
Loan-to-value ratio (no greater than)	80.00%
Loan-to-value ratio that requires private mortgage insurance (in excess of)	80.00%
Maximum | Home equity lines of credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable term	20 years
Loan-to-value ratio (no greater than)	90.00%
Nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Troubled Debt Restructuring	$ 228		2,542
Accrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Troubled Debt Restructuring	$ 3,833		$ 3,932