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Stock-Based Compensation Plans - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Oct. 25, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options outstanding (in shares)	0	0	20,500
Forfeited (in shares)	100
Forfeited (in dollars per share)	$ 42.35
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	7,400	5,625
Fair value of stock award granted (in dollars per share)	$ 50.55	$ 42.35
Forfeited (in shares)	100
Forfeited (in dollars per share)	$ 42.35
Share-based board compensation earned	$ 269	$ 276
Unrecognized compensation cost	$ 705	$ 604
Expected weighted average period of compensation cost recognition (in years)	4 years 6 months	4 years 6 months
Restricted Stock \| Year 1
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage (as a percent)	20.00%
Restricted Stock \| Year 2
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage (as a percent)	20.00%
Restricted Stock \| Year 3
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage (as a percent)	20.00%
Restricted Stock \| Year 4
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage (as a percent)	20.00%
Restricted Stock \| Year 5
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage (as a percent)	20.00%
Stock Options \| Year 1
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage (as a percent)	20.00%
Stock Options \| Year 2
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage (as a percent)	20.00%
Stock Options \| Year 3
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage (as a percent)	20.00%
Stock Options \| Year 4
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage (as a percent)	20.00%
Stock Options \| Year 5
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage (as a percent)	20.00%
2008 Equity Inventive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued (in shares)	0	0	0
2018 Equity Inventive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued (in shares)	7,400	5,625
Number of shares authorized (in shares)				200,000
Options granted in period (in shares)	0	0
2018 Equity Inventive Plan \| Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration term (in years)		10 years