Summary of Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2016	Mar. 31, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Mar. 23, 2015	Jul. 23, 2014
Summary Of Significant Accounting Policies [Line Items]
Deferred costs, net	$ 35,714			$ 35,714		$ 30,042
Unsecured credit facility, net	529,395			529,395		520,956
Senior notes, net of discount and debt issuance costs	291,842			$ 291,842		290,852
Useful life of property				40 years
Depreciation expense from operation	23,800		$ 17,900	$ 67,100	$ 44,700
Real estate cost capitalized excluding interest cost	2,800		2,700	9,100	8,600
Real estate interest cost capitalized incurred	2,500		2,700	8,400	7,100
Amortization of above and below market leases			0		0
Amortization of the deferred financing costs				2,424	2,372
Deferred leasing costs, net	5,112			5,112		6,263
In Place Leases [Member]
Summary Of Significant Accounting Policies [Line Items]
Amortization of lease costs	1,800		400	3,000	1,300
Tenant Relationship [Member]
Summary Of Significant Accounting Policies [Line Items]
Amoritzation of intangible assets	2,300		2,000	7,700	3,000
Amortization adjustment		$ (1,000)				(700)
Platform [Member]
Summary Of Significant Accounting Policies [Line Items]
Amoritzation of intangible assets	800		800	2,400	900
Trade Names [Member]
Summary Of Significant Accounting Policies [Line Items]
Amoritzation of intangible assets	300		300	800	300
Qualitytech, LP [Member]
Summary Of Significant Accounting Policies [Line Items]
Deferred costs, net	35,714			35,714		30,042
Unsecured credit facility, net	529,395			529,395		520,956
Senior notes, net of discount and debt issuance costs	291,842			291,842		290,852
Amortization of the deferred financing costs				2,424	2,372
Real Estate Assets [Member]
Summary Of Significant Accounting Policies [Line Items]
Depreciation expense from operation	20,400		15,200	57,600	38,500
Non-Real Estate Assets [Member]
Summary Of Significant Accounting Policies [Line Items]
Depreciation expense from operation	3,400		$ 2,700	$ 9,500	$ 6,200
Minimum [Member] | Real Property [Member]
Summary Of Significant Accounting Policies [Line Items]
Useful life of property				20 years
Maximum [Member] | Real Property [Member]
Summary Of Significant Accounting Policies [Line Items]
Useful life of property				40 years
Maximum [Member] | Leasehold Improvements [Member]
Summary Of Significant Accounting Policies [Line Items]
Useful life of property				20 years
Unsecured Credit Facility [Member] | Accounting Standards Update 201503 [Member]
Summary Of Significant Accounting Policies [Line Items]
Deferred costs, net						(3,100)
Unsecured credit facility, net						3,100
Senior Notes [Member]
Summary Of Significant Accounting Policies [Line Items]
Interest rate							5.875%	5.875%
Senior notes due				2022
Deferred leasing costs, net	6,300			$ 6,300
Senior Notes [Member] | Accounting Standards Update 201503 [Member]
Summary Of Significant Accounting Policies [Line Items]
Deferred costs, net						(7,100)
Senior notes, net of discount and debt issuance costs						$ 7,100
Rent Expense [Member]
Summary Of Significant Accounting Policies [Line Items]
Amortization of above and below market leases	100			200
Rental Revenue [Member]
Summary Of Significant Accounting Policies [Line Items]
Amortization of above and below market leases	200			400
Carpathia Hosting, Inc. [Member]
Summary Of Significant Accounting Policies [Line Items]
Annual amortization for intangible assets for 2015	10,100			10,100
Annual amortization for intangible assets for 2016	$ 12,200			$ 12,200