AFS Debt Securities in an Unrealized Loss Position (Details) $ in Thousands	Mar. 31, 2020 USD ($) security	Dec. 31, 2019 USD ($) security
Available-for-sale, Fair Value
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions | security	130	88
Less than 12 Months, Fair Value	$ 185,130	$ 289,499
Less than 12 Months, Unrealized Loss	(3,013)	(1,608)
12 Months or More, Fair Value	5,469	46,637
12 Months or More, Unrealized Loss	(29)	(479)
Total, Fair Value	190,599	336,136
Total, Unrealized Loss	$ (3,042)	$ (2,087)
U.S. government and federal agency
Available-for-sale, Fair Value
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions | security	13	20
Less than 12 Months, Fair Value	$ 835	$ 464
Less than 12 Months, Unrealized Loss	(5)	0
12 Months or More, Fair Value	5,442	9,902
12 Months or More, Unrealized Loss	(29)	(65)
Total, Fair Value	6,277	10,366
Total, Unrealized Loss	$ (34)	$ (65)
State and local governments
Available-for-sale, Fair Value
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions | security	64	12
Less than 12 Months, Fair Value	$ 38,635	$ 19,044
Less than 12 Months, Unrealized Loss	(505)	(80)
12 Months or More, Fair Value	0	0
12 Months or More, Unrealized Loss	0	0
Total, Fair Value	38,635	19,044
Total, Unrealized Loss	$ (505)	$ (80)
Corporate bonds
Available-for-sale, Fair Value
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions | security	36	2
Less than 12 Months, Fair Value	$ 137,831	$ 7,378
Less than 12 Months, Unrealized Loss	(2,399)	(1)
12 Months or More, Fair Value	0	0
12 Months or More, Unrealized Loss	0	0
Total, Fair Value	137,831	7,378
Total, Unrealized Loss	$ (2,399)	$ (1)
Residential mortgage-backed securities
Available-for-sale, Fair Value
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions | security	15	35
Less than 12 Months, Fair Value	$ 2,855	$ 85,562
Less than 12 Months, Unrealized Loss	(15)	(234)
12 Months or More, Fair Value	27	29,038
12 Months or More, Unrealized Loss	0	(315)
Total, Fair Value	2,882	114,600
Total, Unrealized Loss	$ (15)	$ (549)
Commercial mortgage-backed securities
Available-for-sale, Fair Value
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions | security	2	19
Less than 12 Months, Fair Value	$ 4,974	$ 177,051
Less than 12 Months, Unrealized Loss	(89)	(1,293)
12 Months or More, Fair Value	0	7,697
12 Months or More, Unrealized Loss	0	(99)
Total, Fair Value	4,974	184,748
Total, Unrealized Loss	$ (89)	$ (1,392)