Loans and Credit Quality - Narrative (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2019 USD ($) financing_commitment contract	Dec. 31, 2018 USD ($) contract
Receivables [Abstract]
Net nonaccrual loans	$ 15,507,000	$ 14,694,000
Nonperforming loans minimum threshold for individual impairment evaluation	50,000
Recorded investment in loans considered to be impaired	27,182,000	31,714,000
Total loans classified as troubled debt restructurings	$ 10,200,000	$ 14,800,000
Number of commitments on TDR | financing_commitment	0
Charge offs on loans later classified as TDRs	$ 64,000
TDR with specific impairment | contract	0	1