Summary of Significant Accounting Policies Summary of Significant Accounting Policies - Summary of the Changes in Level 3 Defined Benefit Plan Assets (Details) - Fair Value, Inputs, Level 3 - W.A. Sanders Coldenhove Holding B.V. - Insurance Contracts Acquired in Business Combination $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation
Fair value of plan assets at beginning of year	$ 0.0
Attributable to Assets Held at December 31	0.2
Attributable to Assets Sold	0.0
Net Purchases/ (Settlements)	0.1
Transfers into/ (out of) Level 3	46.8
Foreign currency effects	1.3
Fair value of plan assets at end of year	$ 48.4