Quarterly Results (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 1,329.8	$ 1,374.7	$ 1,432.5	$ 1,212.5	$ 1,002.3	$ 994.2	$ 1,012.1	$ 972.1	$ 5,349.5	$ 3,980.8	$ 3,407.8
Gross profit	820.5	779.6	689.3	642.0	615.1	607.1	614.1	584.4	2,931.3	2,420.7	1,757.2
Operating income (loss)	284.6	194.7	102.7	132.3	244.1	245.2	225.4	221.6	714.3	936.3	275.8
Net income from continuing operations	$ 174.7	$ 49.2	$ 96.3	$ 35.7	$ 146.7	$ (251.1)	$ 189.2	$ 170.6	$ 355.9	$ 255.4	$ 170.6
Diluted net income per common share (in dollars per share)	$ 0.70	$ 0.20	$ 0.38	$ 0.14	$ 0.58	$ (1.07)	$ 0.77	$ 0.70	$ 1.42	$ 1.03	$ 0.71
Loss on settlement of debt	$ 8.3	$ 0.2	$ 4.1			$ 2.1		$ 13.8	$ 12.6	$ 16.0	$ 43.9	$ 50.6