Securities - Fair Value and Age of Gross Unrealized Losses by Investment Category (Details) $ in Thousands	Dec. 31, 2020 USD ($) security	Dec. 31, 2019 USD ($) security
Number of Securities
Less Than 12 Months | security	3	20
12 Months or More | security	0	7
Total | security	3	27
Fair Value
Less Than 12 Months	$ 36,196	$ 137,097
12 Months or More	0	27,788
Total	36,196	164,885
Unrealized Losses
Less Than 12 Months	(90)	(701)
12 Months or More	0	(252)
Total	$ (90)	$ (953)
U.S. Treasury securities
Number of Securities
Less Than 12 Months | security	0	0
12 Months or More | security	0	0
Total | security	0	0
Fair Value
Less Than 12 Months	$ 0	$ 0
12 Months or More	0	0
Total	0	0
Unrealized Losses
Less Than 12 Months	0	0
12 Months or More	0	0
Total	$ 0	$ 0
Obligations of U.S. government corporations and agencies
Number of Securities
Less Than 12 Months | security	0	3
12 Months or More | security	0	0
Total | security	0	3
Fair Value
Less Than 12 Months	$ 0	$ 22,638
12 Months or More	0	0
Total	0	22,638
Unrealized Losses
Less Than 12 Months	0	(45)
12 Months or More	0	0
Total	$ 0	$ (45)
Collateralized mortgage obligations of U.S. government corporations and agencies
Number of Securities
Less Than 12 Months | security	2	6
12 Months or More | security	0	6
Total | security	2	12
Fair Value
Less Than 12 Months	$ 35,697	$ 23,393
12 Months or More	0	25,254
Total	35,697	48,647
Unrealized Losses
Less Than 12 Months	(89)	(73)
12 Months or More	0	(231)
Total	$ (89)	$ (304)
Residential mortgage-backed securities of U.S. government corporations and agencies
Number of Securities
Less Than 12 Months | security	0	1
12 Months or More | security	0	1
Total | security	0	2
Fair Value
Less Than 12 Months	$ 0	$ 982
12 Months or More	0	2,534
Total	0	3,516
Unrealized Losses
Less Than 12 Months	0	(2)
12 Months or More	0	(21)
Total	$ 0	$ (23)
Commercial mortgage-backed securities of U.S. government corporations and agencies
Number of Securities
Less Than 12 Months | security		9
12 Months or More | security	0	0
Total | security	0	9
Fair Value
Less Than 12 Months		$ 90,005
12 Months or More	0	0
Total	0	90,005
Unrealized Losses
Less Than 12 Months		(581)
12 Months or More	0	0
Total	$ 0	$ (581)
Corporate Obligations
Number of Securities
Less Than 12 Months | security	1	1
12 Months or More | security	0	0
Total | security	1	1
Fair Value
Less Than 12 Months	$ 499	$ 79
12 Months or More	0	0
Total	499	79
Unrealized Losses
Less Than 12 Months	(1)	0
12 Months or More	0	0
Total	$ (1)	$ 0
Obligations of states and political subdivisions
Number of Securities
Less Than 12 Months | security	0	0
12 Months or More | security	0	0
Total | security	0	0
Fair Value
Less Than 12 Months	$ 0	$ 0
12 Months or More	0	0
Total	0	0
Unrealized Losses
Less Than 12 Months	0	0
12 Months or More	0	0
Total	$ 0	$ 0