Revenue Revenue (Details textual) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Jan. 01, 2018
Revenue from Contract with Customer [Abstract]
Contract assets	$ 8.4	$ 14.5
Contract liabilities	13.5	$ 13.8
Contract liability, revenue recognized	28.4
Remaining performance obligation	$ 50.0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-04-01
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Remaining performance obligation, expected timing of satisfaction, percent	53.00%
Remaining performance obligation, expected timing of satisfaction, period	1 year