Summary of Significant Accounting Policies (Narrative) (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($) category	Sep. 30, 2019 USD ($) item	Sep. 30, 2018 USD ($) category
Summary Of Significant Accounting Policies [Line Items]
Operating assets independent of the Operating Partnership	$ 0		$ 0
Maximum exposure to losses	30,700,000		30,700,000
Number of Revenue Categories | category		4		4
Rental	121,475,000	$ 104,760,000	$ 345,841,000	$ 305,774,000
Useful life of property			40 years
Depreciation expense from operation	32,700,000	29,100,000	$ 95,500,000	84,100,000
Real estate cost capitalized excluding interest cost	4,800,000	4,500,000	13,100,000	11,700,000
Real estate interest cost capitalized incurred	8,700,000	6,700,000	24,900,000	18,100,000
Transaction cost			5,800,000
Gain on sale of real estate, net			$ 13,408,000
Number of reporting units | item			1
Reclassification from Other Revenue to Rental Income [Member]
Summary Of Significant Accounting Policies [Line Items]
Prior Period Reclassification Adjustment		1,200,000		5,300,000
Reclassification from Cloud and Managed Services to Other Revenue[Member]
Summary Of Significant Accounting Policies [Line Items]
Prior Period Reclassification Adjustment		7,500,000
Qualitytech, LP
Summary Of Significant Accounting Policies [Line Items]
Operating assets independent of the Operating Partnership	0		$ 0
Rental	$ 121,475,000	104,760,000	345,841,000	305,774,000
Gain on sale of real estate, net			$ 13,408,000
Term Loan Maturing 2025
Summary Of Significant Accounting Policies [Line Items]
Interest rate	4.75%		4.75%
Real Estate Assets
Summary Of Significant Accounting Policies [Line Items]
Depreciation expense from operation	$ 29,800,000	25,800,000	$ 86,800,000	74,400,000
Non-Real Estate Assets
Summary Of Significant Accounting Policies [Line Items]
Depreciation expense from operation	2,900,000	3,300,000	$ 8,700,000	9,700,000
Other | Reclassification from Cloud and Managed Services to Other Revenue[Member]
Summary Of Significant Accounting Policies [Line Items]
Prior Period Reclassification Adjustment				31,700,000
Other | Reclassification Other Revenue [Member]
Summary Of Significant Accounting Policies [Line Items]
Prior Period Reclassification Adjustment				700,000
Recoveries From Customers
Summary Of Significant Accounting Policies [Line Items]
Prior Period Reclassification Adjustment		11,800,000		33,800,000
Minimum | Real Property
Summary Of Significant Accounting Policies [Line Items]
Useful life of property			20 years
Maximum | Real Property
Summary Of Significant Accounting Policies [Line Items]
Useful life of property			40 years
Maximum | Leasehold Improvements
Summary Of Significant Accounting Policies [Line Items]
Useful life of property			20 years
Maximum | Other | Reclassification Other Revenue [Member]
Summary Of Significant Accounting Policies [Line Items]
Prior Period Reclassification Adjustment		100,000
Restructuring Charges [Member]
Summary Of Significant Accounting Policies [Line Items]
Impairment losses	$ 0	$ 3,300,000	$ 0	$ 7,600,000