Stock Options - Schedule of Qualified Stock Option Activity (Details) - Qualified Stock Options - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Shares
Options outstanding at beginning of year (in shares)	100,920	119,720	140,170
Granted (in shares)	18,900	13,950	12,150
Exercised (in shares)	(30,210)	(31,300)	(28,100)
Canceled (in shares)	(2,000)	(1,450)	(4,500)
Options outstanding at end of year (in shares)	87,610	100,920	119,720
Exercise Price
Outstanding at beginning of year, exercise price (in dollars per share)	$ 68.58	$ 57.65	$ 49.78
Granted, exercise price (in dollars per share)	156.38	114.53	105.56
Exercised, exercise price (in dollars per share)	53.68	45.94	38.93
Canceled, exercise price (in dollars per share)	130.92	96.97	58.57
Outstanding at end of year, exercise price (in dollars per share)	$ 91.24	$ 68.58	$ 57.65
Options exercisable at end of year (in shares)	49,360	67,700	85,070
Exercisable at end of year, exercise price (in dollars per share)	$ 61.21	$ 52.60	$ 47.10
Options available for grant at end of year (in shares)	297,850	314,750	327,250