Stock-based Compensation Plans (Summary of Restricted Stock Activity) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Time-based Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Outstanding, beginning of period, Shares	378,256	380,100	350,480
Granted, Shares	155,645	151,193	173,963
Vested, Shares	(136,971)	(123,158)	(119,645)
Forfeited, Shares	(20,304)	(29,879)	(24,698)
Outstanding, end of period, Shares	376,626	378,256	380,100
Outstanding, beginning of period, Weighted Average Grant Date Fair Value	$ 124.88	$ 117.60	$ 116.37
Granted, Weighted Average Grant Date Fair Value	137.59	138.52	115.69
Vested, Weighted Average Grant Date Fair Value	118.70	119.48	111.30
Forfeited, Weighted Average Grant Date Fair Value	131.30	123.60	117.17
Outstanding, end of period, Weighted Average Grant Date Fair Value	$ 132.04	$ 124.88	$ 117.60
Performance-Based and Market-Based Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Outstanding, beginning of period, Shares	119,163	113,848	97,043
Granted, Shares	50,115	47,954	62,143
Vested, Shares	(44,781)	(39,338)	(43,506)
Forfeited, Shares	(3,993)	(3,301)	(1,832)
Outstanding, end of period, Shares	120,504	119,163	113,848
Outstanding, beginning of period, Weighted Average Grant Date Fair Value	$ 122.81	$ 115.92	$ 119.59
Granted, Weighted Average Grant Date Fair Value	137.90	140.36	114.66
Vested, Weighted Average Grant Date Fair Value	114.14	122.42	122.27
Forfeited, Weighted Average Grant Date Fair Value	109.19	120.66	116.90
Outstanding, end of period, Weighted Average Grant Date Fair Value	$ 132.76	$ 122.81	$ 115.92