Summary of Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Mar. 23, 2015	Jul. 23, 2014
Summary Of Significant Accounting Policies [Line Items]
Deferred costs, net		$ 38,507	$ 30,042
Unsecured credit facility, net		634,939	520,956
Senior notes, net of discount and debt issuance costs		$ 292,179	290,852
Useful life of property		40 years
Depreciation expense from operation		$ 90,600	65,000	$ 45,400
Real estate cost capitalized excluding interest cost		11,000	10,800	10,600
Real estate interest cost capitalized incurred		11,400	9,800	6,500
Amortization of below market lease		900	0
Amortization of above and below market leases		200	100	0
Amortization of intangible assets and offsets to revenue in 2017		19,000
Amortization of intangible assets and offsets to revenue in 2018		15,000
Amortization of intangible assets and offsets to revenue in 2019		12,200
Amortization of intangible assets and offsets to revenue in 2020		11,800
Amortization of intangible assets and offsets to revenue in 2021		10,000
Carrying amount of acquired in-place leases		32,100	16,900
Carrying amount of customer relationships		95,700	86,100
Amortization adjustment	$ 1,000		700
Amortization of the deferred financing costs		3,285	3,181	2,673
Deferred leasing costs, net		6,983	6,263
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, net of discount and debt issuance costs			7,100
In Place Leases [Member]
Summary Of Significant Accounting Policies [Line Items]
Accumulated amortization		7,200	2,500
Amortization of lease costs		4,700	1,700	2,200
Tenant Relationship [Member]
Summary Of Significant Accounting Policies [Line Items]
Accumulated amortization		12,400	7,700
Amortization of intangible assets		10,100	5,000	1,300
Platform [Member]
Summary Of Significant Accounting Policies [Line Items]
Amortization of intangible assets		3,200	1,700	0
Trade Names [Member]
Summary Of Significant Accounting Policies [Line Items]
Amortization of intangible assets		1,000	600	0
Qualitytech, LP [Member]
Summary Of Significant Accounting Policies [Line Items]
Deferred costs, net		38,507	30,042
Unsecured credit facility, net		634,939	520,956
Senior notes, net of discount and debt issuance costs		292,179	290,852
Amortization of the deferred financing costs		3,285	3,181	2,673
Real Estate Assets [Member]
Summary Of Significant Accounting Policies [Line Items]
Depreciation expense from operation		77,500	55,200	39,000
Non-Real Estate Assets [Member]
Summary Of Significant Accounting Policies [Line Items]
Depreciation expense from operation		$ 13,100	9,800	$ 6,400
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
Senior Notes [Member]
Summary Of Significant Accounting Policies [Line Items]
Interest rate		5.875%			5.875%	5.875%
Senior notes due		2022
Deferred leasing costs, net		$ 6,100
Senior Notes [Member] | Accounting Standards Update 201503 [Member]
Summary Of Significant Accounting Policies [Line Items]
Deferred costs, net			$ (7,100)
Carpathia Hosting, Inc.
Summary Of Significant Accounting Policies [Line Items]
Annual amortization for intangible assets for 2019		8,000
Annual amortization for intangible assets for 2016		$ 9,900