Stock Options (Schedule of Restricted Stock Award Activity) (Details) - Restricted Stock - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at beginning of year (in shares)	63,052	45,621	32,616
Granted (in shares)	35,300	33,620	27,440
Exercised (in shares)	(22,266)	(16,189)	(11,909)
Canceled (in shares)	(450)	0	(2,526)
Outstanding at end of year (in shares)	75,636	63,052	45,621
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Intrinsic Value [Roll Forward]
Outstanding at beginning of year (in dollars per share)	$ 70.08	$ 54.58	$ 53.31
Granted (in dollars per share)	92.50	84.34	55.17
Exercised (in dollars per share)	66.91	56.03	52.67
Canceled (in dollars per share)	83.99	0	53.57
Outstanding at end of year (in dollars per share)	$ 81.39	$ 70.08	$ 54.58