Acquisitions (Narrative) (Details) $ in Thousands			12 Months Ended
	Oct. 06, 2017 USD ($) ft² MW	Dec. 16, 2016 USD ($) MW	Dec. 31, 2017 USD ($)	Dec. 31, 2015 USD ($)	Dec. 16, 2016 ft²	Dec. 16, 2016 a	Jun. 06, 2016 ft² a MW
Business Acquisition [Line Items]
Capital lease and lease financing obligations assumed | $				$ 43,832
Fort Worth Facility
Business Acquisition [Line Items]
Acquisition costs | $		$ 50,100
Area of facility (in square feet)					262,000	53
Capacity of the plant (in MW) | MW		50
Fort Worth Facility | Basis Of Design
Business Acquisition [Line Items]
Area of facility (in square feet) | ft²					80,000
Piscataway Facility
Business Acquisition [Line Items]
Acres of real estate property | a							38
Area of facility (in square feet) | ft²							360,000
Piscataway Facility | Raised Floor With 18 MW of Critical Power
Business Acquisition [Line Items]
Area of facility (in square feet) | ft²							89,000
Capacity of the plant (in MW) | MW							18
Piscataway Facility | Additional Raised Floor With 8 MW of Additional Critical Power
Business Acquisition [Line Items]
Area of facility (in square feet) | ft²							87,000
Capacity of the plant (in MW) | MW							8
Carpathia Hosting, Inc.
Business Acquisition [Line Items]
Capital lease and lease financing obligations assumed | $			$ 5,700
Vault Campus in Dulles, Virginia
Business Acquisition [Line Items]
Area of facility (in square feet) | ft²	87,000
Capital lease and lease financing obligations assumed | $	$ 17,800
Purchase price of land | $	34,100
Net Purchase Price of Buyout Lease | $	$ 16,300
Vault Campus in Dulles, Virginia | Raised Floor With 13 MW of Critical Power
Business Acquisition [Line Items]
Area of facility (in square feet) | ft²	31,000
Capacity of the plant (in MW) | MW	13