Summary of Significant Accounting Policies - Narrative (Details) $ in Millions	6 Months Ended
	Jun. 30, 2018 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue remaining performance obligation	$ 358.0
Minimum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue Recognition Period	1 day
Maximum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue Recognition Period	3 days