Loans - (Additional Information Related to Accruing TDR's) (Details) - Accruing TDR [Member] - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Loans [Line Items]
Recorded investment	$ 7,620	$ 5,767
Average year-to- date recorded investment	8,039	6,017
Unpaid principal balance	8,007	6,030
Unfunded commitments to fund TDRs	1,815	102
Commercial [Member]
Loans [Line Items]
Recorded investment	5,680	3,302
Average year-to- date recorded investment	6,026	3,440
Unpaid principal balance	6,003	3,464
Unfunded commitments to fund TDRs	1,813	100
Commercial Real Estate [Member]
Loans [Line Items]
Recorded investment	470	538
Average year-to- date recorded investment	499	572
Unpaid principal balance	522	590
Residential Real Estate Segment [Member]
Loans [Line Items]
Recorded investment	1,468	1,920
Average year-to- date recorded investment	1,510	1,996
Unpaid principal balance	1,480	1,969
Unfunded commitments to fund TDRs	2	2
Consumer [Member]
Loans [Line Items]
Recorded investment	2	7
Average year-to- date recorded investment	4	9
Unpaid principal balance	$ 2	$ 7