Schedule III - Real Estate Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Initial costs of land	$ 92,947
Initial costs of buildings and improvements	373,326
Initial costs of construction in progress	349,243
Costs capitalized subsequent to acquisition, land	72,162
Costs capitalized subsequent to acquisition, buildings and improvements	2,465,934
Costs capitalized subsequent to acquisition, construction in progress	679,521
Gross carrying amount, land	165,109
Gross carrying amount, buildings and improvements	2,839,260
Gross carrying amount, construction in progress	1,028,764
Accumulated depreciation and amortization	(702,944)	$ (558,560)	$ (467,644)	$ (394,823)
Owned Properties
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Initial costs of land	92,947
Initial costs of buildings and improvements	312,254
Initial costs of construction in progress	349,243
Costs capitalized subsequent to acquisition, land	72,162
Costs capitalized subsequent to acquisition, buildings and improvements	2,443,381
Costs capitalized subsequent to acquisition, construction in progress	679,142
Gross carrying amount, land	165,109
Gross carrying amount, buildings and improvements	2,755,635
Gross carrying amount, construction in progress	1,028,385
Accumulated depreciation and amortization	(674,468)
Owned Properties | Ashburn, Virginia (DC-1)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Initial costs of land	16,476
Initial costs of buildings and improvements	0
Initial costs of construction in progress	0
Costs capitalized subsequent to acquisition, land	0
Costs capitalized subsequent to acquisition, buildings and improvements	371,725
Costs capitalized subsequent to acquisition, construction in progress	13,653
Gross carrying amount, land	16,476
Gross carrying amount, buildings and improvements	371,725
Gross carrying amount, construction in progress	13,653
Accumulated depreciation and amortization	$ (23,423)
Year of acquisition	2017
Owned Properties | Ashburn, Virginia (DC-2)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Initial costs of land	$ 0
Initial costs of buildings and improvements	0
Initial costs of construction in progress	20,603
Costs capitalized subsequent to acquisition, land	0
Costs capitalized subsequent to acquisition, buildings and improvements	0
Costs capitalized subsequent to acquisition, construction in progress	109,254
Gross carrying amount, land	0
Gross carrying amount, buildings and improvements	0
Gross carrying amount, construction in progress	129,857
Accumulated depreciation and amortization	$ 0
Year of acquisition	2019
Owned Properties | Ashburn, Virginia (DC-3)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Initial costs of land	$ 0
Initial costs of buildings and improvements	0
Initial costs of construction in progress	35,198
Costs capitalized subsequent to acquisition, land	0
Costs capitalized subsequent to acquisition, buildings and improvements	0
Costs capitalized subsequent to acquisition, construction in progress	7,194
Gross carrying amount, land	0
Gross carrying amount, buildings and improvements	0
Gross carrying amount, construction in progress	42,392
Accumulated depreciation and amortization	$ 0
Year of acquisition	2017
Owned Properties | Atlanta, Georgia (DC-1)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Initial costs of land	$ 2,078
Initial costs of buildings and improvements	35,473
Initial costs of construction in progress	2,209
Costs capitalized subsequent to acquisition, land	11,212
Costs capitalized subsequent to acquisition, buildings and improvements	538,751
Costs capitalized subsequent to acquisition, construction in progress	991
Gross carrying amount, land	13,289
Gross carrying amount, buildings and improvements	574,224
Gross carrying amount, construction in progress	3,200
Accumulated depreciation and amortization	$ (221,800)
Year of acquisition	2006
Owned Properties | Atlanta, Georgia (DC-2)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Initial costs of land	$ 10,569
Initial costs of buildings and improvements	0
Initial costs of construction in progress	0
Costs capitalized subsequent to acquisition, land	0
Costs capitalized subsequent to acquisition, buildings and improvements	124,864
Costs capitalized subsequent to acquisition, construction in progress	124,252
Gross carrying amount, land	10,569
Gross carrying amount, buildings and improvements	124,864
Gross carrying amount, construction in progress	124,252
Accumulated depreciation and amortization	$ (2,737)
Year of acquisition	2017
Owned Properties | Atlanta, Georgia Land
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Initial costs of land	$ 23,572
Initial costs of buildings and improvements	0
Initial costs of construction in progress	52,754
Costs capitalized subsequent to acquisition, land	7,726
Costs capitalized subsequent to acquisition, buildings and improvements	1,054
Costs capitalized subsequent to acquisition, construction in progress	10,866
Gross carrying amount, land	31,298
Gross carrying amount, buildings and improvements	1,054
Gross carrying amount, construction in progress	63,619
Accumulated depreciation and amortization	$ (449)
Year of acquisition	2017, 2019, 2020
Owned Properties | Chicago, Illinois
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Initial costs of land	$ 0
Initial costs of buildings and improvements	0
Initial costs of construction in progress	17,764
Costs capitalized subsequent to acquisition, land	9,400
Costs capitalized subsequent to acquisition, buildings and improvements	250,335
Costs capitalized subsequent to acquisition, construction in progress	86,353
Gross carrying amount, land	9,400
Gross carrying amount, buildings and improvements	250,335
Gross carrying amount, construction in progress	104,117
Accumulated depreciation and amortization	$ (34,134)
Year of acquisition	2014
Owned Properties | Dulles, Virginia
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Initial costs of land	$ 3,154
Initial costs of buildings and improvements	29,583
Initial costs of construction in progress	0
Costs capitalized subsequent to acquisition, land	0
Costs capitalized subsequent to acquisition, buildings and improvements	24,740
Costs capitalized subsequent to acquisition, construction in progress	4,148
Gross carrying amount, land	3,154
Gross carrying amount, buildings and improvements	54,323
Gross carrying amount, construction in progress	4,148
Accumulated depreciation and amortization	$ (17,191)
Year of acquisition	2017
Owned Properties | Eemshaven, Netherlands
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Initial costs of land	$ 0
Initial costs of buildings and improvements	0
Initial costs of construction in progress	29,915
Costs capitalized subsequent to acquisition, land	5,366
Costs capitalized subsequent to acquisition, buildings and improvements	21,712
Costs capitalized subsequent to acquisition, construction in progress	17,616
Gross carrying amount, land	5,366
Gross carrying amount, buildings and improvements	21,712
Gross carrying amount, construction in progress	47,531
Accumulated depreciation and amortization	$ (1,017)
Year of acquisition	2019
Owned Properties | Fort Worth, Texas
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Initial costs of land	$ 136
Initial costs of buildings and improvements	610
Initial costs of construction in progress	48,984
Costs capitalized subsequent to acquisition, land	8,943
Costs capitalized subsequent to acquisition, buildings and improvements	123,444
Costs capitalized subsequent to acquisition, construction in progress	(47,920)
Gross carrying amount, land	9,079
Gross carrying amount, buildings and improvements	124,054
Gross carrying amount, construction in progress	1,064
Accumulated depreciation and amortization	$ (8,967)
Year of acquisition	2016
Owned Properties | Groningen, Netherlands
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Initial costs of land	$ 1,743
Initial costs of buildings and improvements	8,640
Initial costs of construction in progress	0
Costs capitalized subsequent to acquisition, land	153
Costs capitalized subsequent to acquisition, buildings and improvements	2,566
Costs capitalized subsequent to acquisition, construction in progress	3,730
Gross carrying amount, land	1,896
Gross carrying amount, buildings and improvements	11,206
Gross carrying amount, construction in progress	3,730
Accumulated depreciation and amortization	$ (1,456)
Year of acquisition	2019
Owned Properties | Hillsboro, Oregon
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Initial costs of land	$ 0
Initial costs of buildings and improvements	0
Initial costs of construction in progress	25,657
Costs capitalized subsequent to acquisition, land	18,414
Costs capitalized subsequent to acquisition, buildings and improvements	34,594
Costs capitalized subsequent to acquisition, construction in progress	52,733
Gross carrying amount, land	18,414
Gross carrying amount, buildings and improvements	34,594
Gross carrying amount, construction in progress	78,390
Accumulated depreciation and amortization	$ (880)
Year of acquisition	2017
Owned Properties | Irving, Texas
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Initial costs of land	$ 0
Initial costs of buildings and improvements	5,808
Initial costs of construction in progress	0
Costs capitalized subsequent to acquisition, land	8,606
Costs capitalized subsequent to acquisition, buildings and improvements	386,467
Costs capitalized subsequent to acquisition, construction in progress	99,591
Gross carrying amount, land	8,606
Gross carrying amount, buildings and improvements	392,275
Gross carrying amount, construction in progress	99,591
Accumulated depreciation and amortization	$ (81,213)
Year of acquisition	2013
Owned Properties | Lenexa, Kansas
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Initial costs of land	$ 400
Initial costs of buildings and improvements	3,100
Initial costs of construction in progress	0
Costs capitalized subsequent to acquisition, land	37
Costs capitalized subsequent to acquisition, buildings and improvements	781
Costs capitalized subsequent to acquisition, construction in progress	0
Gross carrying amount, land	437
Gross carrying amount, buildings and improvements	3,881
Gross carrying amount, construction in progress	0
Accumulated depreciation and amortization	$ (703)
Year of acquisition	2011
Owned Properties | Manassas Virginia (DC-1)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Initial costs of land	$ 0
Initial costs of buildings and improvements	0
Initial costs of construction in progress	27,484
Costs capitalized subsequent to acquisition, land	0
Costs capitalized subsequent to acquisition, buildings and improvements	25
Costs capitalized subsequent to acquisition, construction in progress	33,586
Gross carrying amount, land	0
Gross carrying amount, buildings and improvements	25
Gross carrying amount, construction in progress	61,070
Accumulated depreciation and amortization	$ (2)
Year of acquisition	2018
Owned Properties | Manassas Virginia (DC-2)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Initial costs of land	$ 0
Initial costs of buildings and improvements	0
Initial costs of construction in progress	5,911
Costs capitalized subsequent to acquisition, land	0
Costs capitalized subsequent to acquisition, buildings and improvements	0
Costs capitalized subsequent to acquisition, construction in progress	92
Gross carrying amount, land	0
Gross carrying amount, buildings and improvements	0
Gross carrying amount, construction in progress	6,003
Accumulated depreciation and amortization	$ 0
Year of acquisition	2018
Owned Properties | Miami, Florida
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Initial costs of land	$ 1,777
Initial costs of buildings and improvements	6,955
Initial costs of construction in progress	0
Costs capitalized subsequent to acquisition, land	0
Costs capitalized subsequent to acquisition, buildings and improvements	24,934
Costs capitalized subsequent to acquisition, construction in progress	577
Gross carrying amount, land	1,777
Gross carrying amount, buildings and improvements	31,889
Gross carrying amount, construction in progress	577
Accumulated depreciation and amortization	$ (13,796)
Year of acquisition	2008
Owned Properties | Phoenix, Arizona
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Initial costs of land	$ 0
Initial costs of buildings and improvements	0
Initial costs of construction in progress	24,668
Costs capitalized subsequent to acquisition, land	0
Costs capitalized subsequent to acquisition, buildings and improvements	0
Costs capitalized subsequent to acquisition, construction in progress	13,061
Gross carrying amount, land	0
Gross carrying amount, buildings and improvements	0
Gross carrying amount, construction in progress	37,729
Accumulated depreciation and amortization	$ 0
Year of acquisition	2017
Owned Properties | Piscataway, New Jersey
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Initial costs of land	$ 7,466
Initial costs of buildings and improvements	80,366
Initial costs of construction in progress	13,900
Costs capitalized subsequent to acquisition, land	0
Costs capitalized subsequent to acquisition, buildings and improvements	41,810
Costs capitalized subsequent to acquisition, construction in progress	16,501
Gross carrying amount, land	7,466
Gross carrying amount, buildings and improvements	122,176
Gross carrying amount, construction in progress	30,401
Accumulated depreciation and amortization	$ (16,600)
Year of acquisition	2016
Owned Properties | Princeton, New Jersey
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Initial costs of land	$ 20,700
Initial costs of buildings and improvements	32,126
Initial costs of construction in progress	0
Costs capitalized subsequent to acquisition, land	0
Costs capitalized subsequent to acquisition, buildings and improvements	3,135
Costs capitalized subsequent to acquisition, construction in progress	5
Gross carrying amount, land	20,700
Gross carrying amount, buildings and improvements	35,261
Gross carrying amount, construction in progress	5
Accumulated depreciation and amortization	$ (6,319)
Year of acquisition	2014
Owned Properties | Richmond, Virginia
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Initial costs of land	$ 2,000
Initial costs of buildings and improvements	11,200
Initial costs of construction in progress	7,029
Costs capitalized subsequent to acquisition, land	180
Costs capitalized subsequent to acquisition, buildings and improvements	222,727
Costs capitalized subsequent to acquisition, construction in progress	113,548
Gross carrying amount, land	2,180
Gross carrying amount, buildings and improvements	233,927
Gross carrying amount, construction in progress	120,577
Accumulated depreciation and amortization	$ (84,389)
Year of acquisition	2010 & 2019
Owned Properties | Sacramento, California
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Initial costs of land	$ 1,481
Initial costs of buildings and improvements	52,753
Initial costs of construction in progress	0
Costs capitalized subsequent to acquisition, land	0
Costs capitalized subsequent to acquisition, buildings and improvements	13,546
Costs capitalized subsequent to acquisition, construction in progress	12
Gross carrying amount, land	1,481
Gross carrying amount, buildings and improvements	66,299
Gross carrying amount, construction in progress	12
Accumulated depreciation and amortization	$ (16,325)
Year of acquisition	2012
Owned Properties | San Antonio, Texas
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Initial costs of land	$ 0
Initial costs of buildings and improvements	0
Initial costs of construction in progress	37,167
Costs capitalized subsequent to acquisition, land	0
Costs capitalized subsequent to acquisition, buildings and improvements	0
Costs capitalized subsequent to acquisition, construction in progress	3,213
Gross carrying amount, land	0
Gross carrying amount, buildings and improvements	0
Gross carrying amount, construction in progress	40,380
Accumulated depreciation and amortization	$ 0
Year of acquisition	2020
Owned Properties | Santa Clara, California
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Initial costs of land	$ 0
Initial costs of buildings and improvements	15,838
Initial costs of construction in progress	0
Costs capitalized subsequent to acquisition, land	0
Costs capitalized subsequent to acquisition, buildings and improvements	101,505
Costs capitalized subsequent to acquisition, construction in progress	9,385
Gross carrying amount, land	0
Gross carrying amount, buildings and improvements	117,343
Gross carrying amount, construction in progress	9,385
Accumulated depreciation and amortization	$ (52,742)
Year of acquisition	2007
Owned Properties | Suwanee, Georgia (Atlanta-Suwanee)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Initial costs of land	$ 1,395
Initial costs of buildings and improvements	29,802
Initial costs of construction in progress	0
Costs capitalized subsequent to acquisition, land	2,126
Costs capitalized subsequent to acquisition, buildings and improvements	154,665
Costs capitalized subsequent to acquisition, construction in progress	6,701
Gross carrying amount, land	3,521
Gross carrying amount, buildings and improvements	184,467
Gross carrying amount, construction in progress	6,701
Accumulated depreciation and amortization	$ (90,323)
Year of acquisition	2005
Leased Properties
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Initial costs of land	$ 0
Initial costs of buildings and improvements	61,072
Initial costs of construction in progress	0
Costs capitalized subsequent to acquisition, land	0
Costs capitalized subsequent to acquisition, buildings and improvements	22,553
Costs capitalized subsequent to acquisition, construction in progress	379
Gross carrying amount, land	0
Gross carrying amount, buildings and improvements	83,625
Gross carrying amount, construction in progress	379
Accumulated depreciation and amortization	(28,476)
Leased Properties | Jersey City, New Jersey
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Initial costs of land	0
Initial costs of buildings and improvements	1,985
Initial costs of construction in progress	0
Costs capitalized subsequent to acquisition, land	0
Costs capitalized subsequent to acquisition, buildings and improvements	28,178
Costs capitalized subsequent to acquisition, construction in progress	223
Gross carrying amount, land	0
Gross carrying amount, buildings and improvements	30,163
Gross carrying amount, construction in progress	223
Accumulated depreciation and amortization	$ (15,455)
Year of acquisition	2006
Leased Properties | Overland Park, Kansas
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Initial costs of land	$ 0
Initial costs of buildings and improvements	0
Initial costs of construction in progress	0
Costs capitalized subsequent to acquisition, land	0
Costs capitalized subsequent to acquisition, buildings and improvements	866
Costs capitalized subsequent to acquisition, construction in progress	154
Gross carrying amount, land	0
Gross carrying amount, buildings and improvements	866
Gross carrying amount, construction in progress	154
Accumulated depreciation and amortization	(508)
Lease Facilities acquired in 2015
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Initial costs of land	0
Initial costs of buildings and improvements	59,087
Initial costs of construction in progress	0
Costs capitalized subsequent to acquisition, land	0
Costs capitalized subsequent to acquisition, buildings and improvements	(6,491)
Costs capitalized subsequent to acquisition, construction in progress	2
Gross carrying amount, land	0
Gross carrying amount, buildings and improvements	52,596
Gross carrying amount, construction in progress	2
Accumulated depreciation and amortization	$ (12,513)
Year of acquisition	2015