Investment Securities - Credit Quality Indicator (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Net carrying amount	$ 54,377	$ 40,927
State and political subdivisions
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Net carrying amount	26,082	27,082
Other securities
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Net carrying amount	1,174	$ 3,049
Aaa/AAA | State and political subdivisions
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Net carrying amount	2,111
Aaa/AAA | Other securities
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Net carrying amount	0
Aa/AA | State and political subdivisions
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Net carrying amount	19,084
Aa/AA | Other securities
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Net carrying amount	0
A | State and political subdivisions
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Net carrying amount	1,695
A | Other securities
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Net carrying amount	0
Not Rated | State and political subdivisions
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Net carrying amount	3,192
Not Rated | Other securities
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Net carrying amount	1,174
Not Guaranteed or Pre-Refunded | State and political subdivisions
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Net carrying amount	17,796
Not Guaranteed or Pre-Refunded | Aaa/AAA | State and political subdivisions
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Net carrying amount	2,111
Not Guaranteed or Pre-Refunded | Aa/AA | State and political subdivisions
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Net carrying amount	12,596
Not Guaranteed or Pre-Refunded | A | State and political subdivisions
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Net carrying amount	766
Not Guaranteed or Pre-Refunded | Not Rated | State and political subdivisions
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Net carrying amount	2,323
Other Credit Enhancement or Insurance | State and political subdivisions
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Net carrying amount	7,502
Other Credit Enhancement or Insurance | Aaa/AAA | State and political subdivisions
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Net carrying amount	0
Other Credit Enhancement or Insurance | Aa/AA | State and political subdivisions
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Net carrying amount	6,203
Other Credit Enhancement or Insurance | A | State and political subdivisions
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Net carrying amount	929
Other Credit Enhancement or Insurance | Not Rated | State and political subdivisions
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Net carrying amount	370
Pre-Refunded | State and political subdivisions
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Net carrying amount	784
Pre-Refunded | Aaa/AAA | State and political subdivisions
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Net carrying amount	0
Pre-Refunded | Aa/AA | State and political subdivisions
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Net carrying amount	285
Pre-Refunded | A | State and political subdivisions
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Net carrying amount	0
Pre-Refunded | Not Rated | State and political subdivisions
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Net carrying amount	$ 499