Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Interest expense on income taxes	$ (1.1)	$ 0.3	$ 0.0
Accrued interest on income taxes	0.4	1.4	1.3
Potential penalty expense	0.2
Total accrued liabilities	0.2
Significant change in unrecognized tax benefits is reasonably possible, amount of unrecorded benefit	(2.8)
Potential benefit on the effective tax rate	6.0
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits beginning balance	11.8	12.8	5.0
Reductions for tax positions due to lapsed statutes of limitations			(0.4)
Additions for business combinations			8.4
Foreign exchange fluctuations		(0.5)	(0.2)
Additions based on tax positions related to the current year	2.6
Additions for tax positions of prior years	0.6
Reductions for tax positions due to lapsed statutes of limitations	1.3	0.5
Tax reform	(1.5)
Foreign exchange fluctuations	0.3
Unrecognized tax benefits ending balance	12.5	11.8	$ 12.8
Deferred tax liability, provisional income tax benefit	(5.6)
Amount of change in deferred tax assets valuation allowance	11.7
Provisional tax benefit	(18.0)
Transition tax liability	25.9	$ 0.0
Deferred tax asset, provisional income tax expense	$ 7.9