Summary of Significant Accounting Policies (Details)	3 Months Ended									12 Months Ended
	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2018 USD ($) segment	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Jan. 01, 2019 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of Operating Segments | segment										1
Goodwill [Roll Forward]
Balance as of December 31, 2017				$ 3,389,595,000						$ 3,389,595,000
Merger / Acquisition										982,667,000
Impact of Change in Foreign Exchange Rates										(24,255,000)
Balance as of December 31, 2018	$ 4,348,007,000				$ 3,389,595,000					$ 4,348,007,000	$ 3,389,595,000
Period in which short-term investment become cash equivalents										90 days
Interest capitalized										$ 34,700,000	21,700,000	$ 16,300,000
Compensation costs, leasing and construction activities										74,100,000	77,300,000	70,700,000
Deferred leasing costs, net	322,200,000				330,900,000					322,200,000	330,900,000
Amortization expense on deferred leasing costs	72,900,000				50,100,000				$ 43,800,000	72,900,000	50,100,000	43,800,000
Assets or liabilities for uncertain tax positions	0				0					0	0
Interest or penalties from uncertain tax positions										0	0	0
Non-cash gain on lease termination									29,200,000
Asset retirement obligations	17,500,000				12,500,000					17,500,000	12,500,000
Proceeds from sale of real estate										291,700,000
Gain (loss) on sale										$ 80,400,000	39,900,000
Number of reportable segments | segment										1
Operating revenue	778,267,000	$ 768,924,000	$ 754,919,000	744,368,000	731,445,000	$ 609,925,000	$ 565,989,000	$ 550,569,000		$ 3,046,478,000	2,457,928,000	2,142,213,000
Investments in real estate	15,079,726,000				13,841,186,000					15,079,726,000	13,841,186,000
Interconnection Revenue [Member]
Goodwill [Roll Forward]
Prior period reclassifications											(235,700,000)	(204,300,000)
Rental and Other Services
Goodwill [Roll Forward]
Prior period reclassifications											235,700,000	204,300,000
United States
Goodwill [Roll Forward]
Operating revenue										2,482,100,000	1,942,700,000	1,670,200,000
Investments in real estate	11,100,000,000				10,500,000,000				6,300,000,000	11,100,000,000	10,500,000,000	6,300,000,000
Non-US
Goodwill [Roll Forward]
Operating revenue										564,400,000	515,200,000	442,900,000
Investments in real estate	3,800,000,000				3,100,000,000				2,600,000,000	3,800,000,000	3,100,000,000	2,600,000,000
United Kingdom
Goodwill [Roll Forward]
Operating revenue										295,300,000	275,100,000	234,300,000
Investments in real estate	1,600,000,000				1,700,000,000				$ 1,500,000,000	$ 1,600,000,000	$ 1,700,000,000	$ 1,500,000,000
United Kingdom | Sales | Geographic Concentration Risk
Goodwill [Roll Forward]
Concentration risk										9.70%	11.20%	11.10%
United Kingdom | Long-Lived Assets | Geographic Concentration Risk
Goodwill [Roll Forward]
Concentration risk										10.90%	12.10%	16.60%
ASU 2016-02
Goodwill [Roll Forward]
Percent of revenues										97.00%
Estimated direct costs to be expensed if Topic 842 had been in effect										$ 37,000,000
ASU 2016-02 | Scenario, Forecast | Minimum
Goodwill [Roll Forward]
Lease liability													$ 700,000,000
Right-of-use asset													625,000,000
ASU 2016-02 | Scenario, Forecast | Maximum
Goodwill [Roll Forward]
Lease liability													900,000,000
Right-of-use asset													$ 825,000,000
ASU 2014-09
Goodwill [Roll Forward]
Percent of revenues										3.00%
Buildings and improvements | Minimum
Goodwill [Roll Forward]
Building and improvements, useful life										5 years
Buildings and improvements | Maximum
Goodwill [Roll Forward]
Building and improvements, useful life										39 years
Machinery and equipment | Minimum
Goodwill [Roll Forward]
Building and improvements, useful life										7 years
Machinery and equipment | Maximum
Goodwill [Roll Forward]
Building and improvements, useful life										15 years
Furniture and Fixtures | Minimum
Goodwill [Roll Forward]
Building and improvements, useful life										3 years
Furniture and Fixtures | Maximum
Goodwill [Roll Forward]
Building and improvements, useful life										5 years
Telx Acquisition
Goodwill [Roll Forward]
Balance as of December 31, 2017				330,845,000						$ 330,845,000
Merger / Acquisition										0
Impact of Change in Foreign Exchange Rates										0
Balance as of December 31, 2018	330,845,000				330,845,000					330,845,000	$ 330,845,000
European Portfolio Acquisition
Goodwill [Roll Forward]
Balance as of December 31, 2017				466,604,000						466,604,000
Merger / Acquisition										0
Impact of Change in Foreign Exchange Rates										(24,255,000)
Balance as of December 31, 2018	442,349,000				466,604,000					442,349,000	466,604,000
DFT Merger
Goodwill [Roll Forward]
Balance as of December 31, 2017				2,592,146,000						2,592,146,000
Merger / Acquisition										0
Impact of Change in Foreign Exchange Rates										0
Balance as of December 31, 2018	2,592,146,000				2,592,146,000					2,592,146,000	2,592,146,000
Ascenty Acquisition
Goodwill [Roll Forward]
Balance as of December 31, 2017				$ 0						0
Merger / Acquisition										982,667,000
Impact of Change in Foreign Exchange Rates										0
Balance as of December 31, 2018	$ 982,667,000				$ 0					$ 982,667,000	$ 0