Securities - Contractual Maturities and Realized Gains and Losses (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Amortized Cost
Due in one year or less	$ 42,920		$ 42,920
Due after one year through five years	140,007		140,007
Due after five years through ten years	12,132		12,132
Due after ten years	3,740		3,740
Amortized Cost	198,799		198,799		$ 216,650
Estimated Fair Value
Due in one year or less	43,031		43,031
Due after one year through five years	141,051		141,051
Due after five years through ten years	12,341		12,341
Due after ten years	4,004		4,004
Fair Value	200,427		200,427		$ 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	1		5	$ 5
Gross realized losses from maturities and calls of securities available for sale		$ (1)		(1)
Net realized losses from maturities and calls of securities available for sale	1	(1)	5	4
Proceeds from maturities and calls and paydowns of securities	$ 17,982	$ 9,668	$ 33,639	$ 22,402

[1] Derived from audited consolidated financial statements.