Securities - Contractual Maturities and Realized Gains and Losses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Amortized Cost
Due in one year or less	$ 37,681		$ 37,681
Due after one year through five years	133,691		133,691
Due after five years through ten years	12,834		12,834
Due after ten years	4,670		4,670
Amortized Cost	188,876		188,876		$ 216,650
Estimated Fair Value
Due in one year or less	37,796		37,796
Due after one year through five years	135,024		135,024
Due after five years through ten years	13,066		13,066
Due after ten years	4,983		4,983
Fair Value	190,869		190,869		$ 214,910	[1]
Gross realized gains and losses on and the proceeds from the maturities, calls and paydowns of securities
Gross realized gains from maturities and calls of securities available for sale	3	$ 5	8	$ 10
Gross realized losses from maturities and calls of securities available for sale				(1)
Net realized losses from maturities and calls of securities available for sale	3	5	8	9
Proceeds from maturities and calls and paydowns of securities	$ 21,954	$ 12,865	$ 55,593	$ 35,267

[1] Derived from audited consolidated financial statements.