Securities - Summary of debt securites held-to-maturity in unrealized loss position (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Summary of held to maturity securities in an unrealized loss position
Fair Value, Less than 12 Months	$ 1,589	$ 48,007
Unrealized Loss, Less than 12 Months	11	160
Fair Value, 12 Months or More	1,907	49,922
Unrealized Loss, 12 Months or More	56	684
Fair Value, Total	3,496	97,929
Unrealized Loss, Total	67	844
State and political subdivisions
Summary of held to maturity securities in an unrealized loss position
Fair Value, Less than 12 Months		10,117
Unrealized Loss, Less than 12 Months		9
Fair Value, 12 Months or More		0
Unrealized Loss, 12 Months or More		0
Fair Value, Total		10,117
Unrealized Loss, Total		9
Residential mortgage-backed securities, Agency
Summary of held to maturity securities in an unrealized loss position
Fair Value, Less than 12 Months	1,589	16,049
Unrealized Loss, Less than 12 Months	11	64
Fair Value, 12 Months or More	440	48,237
Unrealized Loss, 12 Months or More	3	630
Fair Value, Total	2,029	64,286
Unrealized Loss, Total	14	694
Commercial mortgage-backed, Agency
Summary of held to maturity securities in an unrealized loss position
Fair Value, Less than 12 Months	0	21,841
Unrealized Loss, Less than 12 Months	0	87
Fair Value, 12 Months or More	1,467	1,685
Unrealized Loss, 12 Months or More	53	54
Fair Value, Total	1,467	23,526
Unrealized Loss, Total	$ 53	$ 141