Significant Accounting Policies, New Accounting Guidance (Details) - USD ($) $ 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
New Accounting Guidance [Abstract]
Deferred income taxes	$ 97.1				$ 96.9				$ 97.1	$ 96.9
Equity	533.9				490.1				533.9	490.1
Net sales	556.7	$ 541.0	$ 548.9	$ 566.1	566.6	$ 512.7	$ 508.3	$ 515.5	2,212.7	2,103.1	$ 1,503.0
Retained earnings	472.1				394.9				472.1	394.9
ASU 2016-16 [Member]
New Accounting Guidance [Abstract]
Deferred income taxes					0.0					0.0
Retained earnings					(8.3)					(8.3)
ASU 2016-09 [Member]
New Accounting Guidance [Abstract]
Deferred income taxes											0.4
Equity											$ 0.4
ASU 2014-09 [Member]
New Accounting Guidance [Abstract]
Deferred income taxes					(0.2)					(0.2)
Retained earnings					0.7					0.7
ASU 2014-09 [Member] | Maximum [Member]
New Accounting Guidance [Abstract]
Retained earnings					0.7					0.7
ASU 2014-09 [Member] | Effect of Adoption of ASC 606 [Member]
New Accounting Guidance [Abstract]
Deferred income taxes	0.6								0.6
Net sales									(4.4)	3.0
Retained earnings	$ (2.7)				$ 0.7				$ (2.7)	$ 0.7