Summary of Significant Accounting Policies - Deferred Offering Costs, Revenue Recognition, Equity-Based Compensation, and Advertising Costs (Details) - USD ($)	1 Months Ended	12 Months Ended
	Oct. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Significant Accounting Policies [Line Items]
Adjustments to additional paid-in capital, deferred offering costs	$ 4,900,000
Deferred offering costs			$ 0
Advertising expense		$ 1,800,000	$ 2,200,000	$ 1,600,000
Colocation Contracts
Significant Accounting Policies [Line Items]
Expected life of installations		66 months	73 months
Broadband Services Contracts
Significant Accounting Policies [Line Items]
Expected life of installations		29 months	34 months
External Connectivity Contracts
Significant Accounting Policies [Line Items]
Expected life of installations		41 months	35 months
Minimum
Significant Accounting Policies [Line Items]
Length of contract		3 years
Maximum
Significant Accounting Policies [Line Items]
Length of contract		5 years
Revenue | Product Concentration Risk | Colocation and Connectivity Services
Significant Accounting Policies [Line Items]
Percentage of concentration risk		95.00%	95.00%	95.00%