Revenue and Customers - Additional Information (Details)	6 Months Ended
	Jun. 30, 2018
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Payment term	30 days
Minimum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Contract term	2 months
Maximum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Contract term	60 months