Quarterly Financial and Market Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Schedule Of Quarterly Financial Information [Line Items]
Net sales	$ 564.3	$ 572.5	$ 609.0	$ 609.9	$ 561.0	$ 540.5	$ 547.5	$ 540.1	$ 2,355.7	$ 2,189.1	$ 1,973.3
Gross margin	146.5	157.9	168.8	167.2	150.4	143.0	144.8	142.6	640.4	580.8	551.8
Operating income	97.4	109.9	115.1	102.8	95.8	96.5	96.5	82.4	$ 425.2	$ 371.2	$ 350.6
Net income	$ 73.2	$ 80.3	$ 80.9	$ 72.2	$ 66.1	$ 80.1	$ 68.8	$ 61.6
Net income per common share:
Basic	$ 0.87	$ 0.94	$ 0.95	$ 0.85	$ 0.78	$ 0.92	$ 0.77	$ 0.68
Diluted	0.86	0.93	0.94	0.84	0.76	0.91	0.76	0.68
Maximum
Market price:
Common Stock Value during the Period	80.29	85.33	80.88	72.65	67.44	69.92	73.26	69.08
Minimum
Market price:
Common Stock Value during the Period	$ 73.31	$ 77.01	$ 68.00	$ 56.18	$ 53.76	$ 65.30	$ 63.37	$ 61.67