Business Acquisitions - Pro-forma Nonrecurring Adjustments (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net income (loss)	$ 58.3	$ 62.8
Diluted (USD per share)	$ 1.05	$ 1.13
Acquisition-related costs, current period
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net income (loss)	$ 10.3	$ (10.3)
Diluted (USD per share)	$ 0.15	$ (0.14)
Acquisition-related costs, prior period
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net income (loss)	$ 0.0	$ (7.1)
Diluted (USD per share)	$ 0.00	$ (0.11)
Intangible amortization and inventory step up
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net income (loss)	$ 1.6	$ (16.9)
Diluted (USD per share)	$ 0.02	$ (0.19)
Interest expense
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net income (loss)	$ (2.1)	$ (7.2)
Diluted (USD per share)	$ (0.03)	$ (0.08)