Stock-Based Compensation, Restricted Shares (Details) - Restricted Shares - 2012 Directors Restricted Stock Plan - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Stock-Based Compensation
Remaining shares available for the granting of stock options under plan	141,359
Restricted share activity
Restricted shares outstanding at the beginning of the period (in shares)	21,061
Restricted shares granted (in shares)	0
Restricted shares outstanding at the end of the period (in shares)	21,061	21,061
Fair Value at Grant Date
Fair value at the grant date, restricted shares outstanding at the beginning of the period (in dollars per share)	$ 66.92
Fair value of restricted shares granted (in dollars per share)	0
Fair value at the grant date, restricted shares outstanding at the end of the period (in dollars per share)	$ 66.92	$ 66.92
Weighted Average Remaining Amortization Term (in years)	1 month 17 days	4 months 17 days
Total compensation cost related to non-vested restricted shares not yet recognized (in dollars)	$ 0.2
Weighted average expected amortization period	1 month 17 days