Stock-Based Compensation Plans - Nonvested Performance Awards Granted (Details) - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Performance awards
Granted (in shares)		0	0
Performance awards
Performance awards
Outstanding at the beginning of the period (in shares)	241,921	253,432	267,129
Granted (in shares)	138,033	77,182	80,512
Increase (decrease) in awards based on performance (in shares)	(37,469)	18,112	(16,760)
Converted to restricted stock (in shares)		(96,317)	(73,072)
Share-based Compensation Arrangement By Share-based Payment Award, Equity Instruments Other Than Options, Converted to Common Shares	(56,545)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Converted to Common Shares, Weighted Average Grant Date Fair Value	$ 156.00
Forfeited (in shares)	(1,418)	(10,488)	(4,377)
Outstanding at the ending of the period (in shares)	284,522	241,921	253,432
Weighted average grant date fair value per award
Outstanding at the beginning of the period (in dollars per share)	$ 195.13	$ 176.27	$ 157.21
Granted (in dollars per share)	191.12	238.03	200.75
Change in awards based on performance (in dollars per share)	156.00	177.26	142.03
Converted to restricted stock (in dollars per share)		177.26	142.03
Forfeited (in dollars per share)	207.65	188.52	166.44
Outstanding at the ending of the period (in dollars per share)	$ 206.05	$ 195.13	$ 176.27
Grants in period based on shareholder metrics (in shares)	69,064	38,823	47,502
Grants in period based on financial metrics (in shares)	68,969	38,359	33,010