Industry Segments and Geographic Area Information - Geographic Area (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net Sales:
Net sales	$ 917.7	$ 950.5	$ 948.3	$ 852.3	$ 854.2	$ 907.4	$ 908.8	$ 834.8	$ 3,668.8	$ 3,505.2	$ 3,390.4
Operating Income:
Operating Income									503.7	477.8	474.6
Long-lived Assets:
Long-Lived Assets	2,110.2				1,963.0				2,110.2	1,963.0	1,814.8
United States
Net Sales:
Net sales									3,280.9	3,147.4	3,008.4
Operating Income:
Operating Income									422.1	419.1	426.1
Long-lived Assets:
Long-Lived Assets	1,877.4				1,762.9				1,877.4	1,762.9	1,627.7
International
Net Sales:
Net sales									387.9	357.8	382.0
Operating Income:
Operating Income									81.6	58.7	48.5
Long-lived Assets:
Long-Lived Assets	$ 232.8				$ 200.1				$ 232.8	$ 200.1	$ 187.1