Securities - Gross Unrealized Losses and Fair Value of Company's Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Schedule of Available-for-sale Securities [Line Items]
Fair Value less than 12 months	$ 179,722	$ 224,138
Fair value more than 12 months	7,336	67,402
Total fair value	187,058	291,540
Unrealized losses less than 12 months	(4,140)	(2,788)
Unrealized losses more than 12 months	(282)	(574)
Total unrealized losses	(4,422)	(3,362)
U.S. Treasury and federal agencies
Schedule of Available-for-sale Securities [Line Items]
Fair Value less than 12 months		1,413
Fair value more than 12 months		0
Total fair value		1,413
Unrealized losses less than 12 months		(2)
Unrealized losses more than 12 months		0
Total unrealized losses		(2)
State and municipal
Schedule of Available-for-sale Securities [Line Items]
Fair Value less than 12 months	152,037	129,942
Fair value more than 12 months	7,336	6,279
Total fair value	159,373	136,221
Unrealized losses less than 12 months	(3,956)	(2,374)
Unrealized losses more than 12 months	(282)	(131)
Total unrealized losses	(4,238)	(2,505)
Federal agency collateralized mortgage obligations
Schedule of Available-for-sale Securities [Line Items]
Fair Value less than 12 months	27,685	68,043
Fair value more than 12 months	0	23,301
Total fair value	27,685	91,344
Unrealized losses less than 12 months	(184)	(308)
Unrealized losses more than 12 months	0	(260)
Total unrealized losses	$ (184)	(568)
Federal agency mortgage-backed pools
Schedule of Available-for-sale Securities [Line Items]
Fair Value less than 12 months		24,740
Fair value more than 12 months		37,822
Total fair value		62,562
Unrealized losses less than 12 months		(104)
Unrealized losses more than 12 months		(183)
Total unrealized losses		(287)
Corporate notes
Schedule of Available-for-sale Securities [Line Items]
Fair Value less than 12 months		0
Fair value more than 12 months		0
Total fair value		0
Unrealized losses less than 12 months		0
Unrealized losses more than 12 months		0
Total unrealized losses		$ 0