Share-Based Compensation Plan - Activity in stock (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Additional disclosures
Compensation expense	$ 3.1	$ 1.9	$ 1.5
Restricted Stock Awards and Units.
Restricted Stock Awards and Units
Outstanding at beginning of period	325,030	347,211
Granted	66,664	82,494
Vested	(104,119)	(91,346)
Forfeited or cancelled	(26,725)	(13,329)
Outstanding at end of period	260,850	325,030	347,211
Weighted Average Grant Date Fair Value
Outstanding at beginning of period	$ 19.48	$ 18.64
Granted	26.63	19.62
Vested	20.51	16.39
Forfeited or cancelled	18.03	19.62
Outstanding at end of period	$ 21.04	$ 19.48	$ 18.64
Additional disclosures
Unrecognized compensation cost	$ 2.2	$ 2.8
Weighted average period	2 years 10 months 28 days	3 years 10 months 9 days
2009 Plan \| Restricted stock awards
Restricted Stock Awards and Units
Outstanding at beginning of period	203,253
Outstanding at end of period	140,228	203,253
2009 Plan \| Restricted stock units
Restricted Stock Awards and Units
Outstanding at beginning of period	121,777
Outstanding at end of period	120,622	121,777

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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