Borrowings - Long-term Debt (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Long-term debt
Notes payable, FHLB, ranging in original maturity from seven to ten years, collateralized by FHLB deposits, residential and commercial real estate loans and FHLB stock	$ 35,606	$ 50,000
Notes Payable	49,500
Total long-term borrowings	$ 85,106	$ 50,000
FHLB advances
Long-term debt
Weighted average rate (as a percent)	1.80%	2.28%
FHLB advances | Minimum
Long-term debt
Notes payable original maturity term	7 years	7 years
Interest rate (as a percent)	1.57%	2.20%
FHLB advances | Maximum
Long-term debt
Notes payable original maturity term	10 years	10 years
Interest rate (as a percent)	3.04%	2.41%