Revenue Recognition - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Oct. 01, 2017	Sep. 30, 2018	Oct. 01, 2017	Jan. 01, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accumulated deficit	$ 729.2		$ 729.2			$ 720.8
Revenue	159.4	$ 157.1	453.6	$ 437.0
Remaining performance obligation	571.7		571.7
Contract assets, Net change			26.7
Contract liabilities, Net change			(4.0)
Revenue recognized	14.5		33.1
Effect of Change Higher/(Lower)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue	5.3		21.0
Cost of revenue	3.8		15.5
ASC 606
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accumulated deficit					$ 721.0
ASC 606 | Effect of Change Higher/(Lower)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accumulated deficit	(5.5)		(5.5)
Revenue	$ 5.3		$ 21.0
ASC 606 Adjustment | ASC 606
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accumulated deficit					$ 0.2