Stock-Based Compensation Plans - Restricted Stock Activity (Details) - $ / shares	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Restricted stock
Restricted stock shares
Equity instruments outstanding at the beginning of the period (in shares)	157,066
Granted (in shares)	81,807	94,641
Vested (in shares)	(71,291)
Forfeited (in shares)	(2,792)
Equity instruments outstanding at the end of the period (in shares)	164,790
Restricted stock shares weighted average grant date fair value per share
Equity instruments outstanding at the beginning of the period (in dollars per share)	$ 192.90
Grant date fair value per share (in dollars per share)	235.14
Vested (in dollars per share)	195.96
Forfeited (in dollars per share)	217.62
Equity instruments outstanding at the end of the period (in dollars per share)	$ 212.12
Restricted Stock Converted From Performance Shares
Restricted stock shares
Equity instruments outstanding at the beginning of the period (in shares)	74,627
Granted (in shares)	0
Vested (in shares)	(47,335)
Forfeited (in shares)	(86)
Equity instruments outstanding at the end of the period (in shares)	27,206