Revenue Recognition - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($)
Revenue from Contract with Customer [Abstract]
Increase in net contract assets (liabilities) during period	$ 62.1
Revenue recognized that was previously in contract liabilities	132.5
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	3,900.0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 1,800.0
Percentage of remaining performance obligations expected to be satisfied	47.00%
Period for remaining performance obligation expected timing of satisfaction	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Percentage of remaining performance obligations expected to be satisfied	27.00%
Period for remaining performance obligation expected timing of satisfaction	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Percentage of remaining performance obligations expected to be satisfied	26.00%
Period for remaining performance obligation expected timing of satisfaction