Real Estate Assets and Construction in Progress (Summary of Owned or Leased Properties by the Company) (Details) $ in Thousands	Sep. 30, 2019 USD ($) facility	Dec. 31, 2018 USD ($) facility
Real Estate Properties [Line Items]
Land	$ 127,587	$ 105,541
Buildings, Improvements and Equipment	2,155,810	1,917,251
Construction in progress	843,754	790,064
Manassas, Virginia | Assets Held For Sale
Real Estate Properties [Line Items]
Construction in progress		71,000
Owned Properties
Real Estate Properties [Line Items]
Land	127,587	105,541
Buildings, Improvements and Equipment	2,155,810	1,917,251
Construction in progress	843,754	790,064
Total cost	3,127,151	2,812,856
Owned Properties | Atlanta, Georgia (Atlanta-Metro)
Real Estate Properties [Line Items]
Land	21,016	20,416
Buildings, Improvements and Equipment	523,859	493,446
Construction in progress	115,354	88,253
Total cost	660,229	602,115
Owned Properties | Irving Texas
Real Estate Properties [Line Items]
Land	8,606	8,606
Buildings, Improvements and Equipment	347,067	345,615
Construction in progress	113,696	99,445
Total cost	469,369	453,666
Owned Properties | Richmond, Virginia
Real Estate Properties [Line Items]
Land	2,180	2,180
Buildings, Improvements and Equipment	254,495	253,098
Construction in progress	72,882	67,932
Total cost	329,557	323,210
Owned Properties | Ashburn, Virginia
Real Estate Properties [Line Items]
Land	37,079	17,325
Buildings, Improvements and Equipment	131,695	63,245
Construction in progress	144,930	184,951
Total cost	313,704	265,521
Owned Properties | Chicago, Illinois
Real Estate Properties [Line Items]
Land	9,400	9,400
Buildings, Improvements and Equipment	153,582	130,150
Construction in progress	133,521	133,095
Total cost	296,503	272,645
Owned Properties | Suwanee, Georgia (Atlanta-Suwanee)
Real Estate Properties [Line Items]
Land	3,521	3,521
Buildings, Improvements and Equipment	170,396	166,298
Construction in progress	2,833	3,188
Total cost	176,750	173,007
Owned Properties | Piscataway New Jersey
Real Estate Properties [Line Items]
Land	7,466	7,466
Buildings, Improvements and Equipment	98,723	97,806
Construction in progress	37,592	33,472
Total cost	143,781	138,744
Owned Properties | Santa Clara, California
Real Estate Properties [Line Items]
Buildings, Improvements and Equipment	105,759	98,548
Construction in progress	6,956	7,600
Total cost	112,715	106,148
Owned Properties | Fort Worth, Texas
Real Estate Properties [Line Items]
Land	9,079	9,079
Buildings, Improvements and Equipment	55,019	18,623
Construction in progress	26,892	43,715
Total cost	90,990	71,417
Owned Properties | Dulles, Virginia
Real Estate Properties [Line Items]
Land	3,154	3,154
Buildings, Improvements and Equipment	73,373	72,435
Construction in progress	4,222	3,852
Total cost	80,749	79,441
Owned Properties | Sacramento, California
Real Estate Properties [Line Items]
Land	1,481	1,481
Buildings, Improvements and Equipment	64,997	64,874
Construction in progress	52	92
Total cost	66,530	66,447
Owned Properties | Manassas, Virginia
Real Estate Properties [Line Items]
Construction in progress	58,741	45,194
Total cost	58,741	45,194
Owned Properties | Hillsboro, Oregon
Real Estate Properties [Line Items]
Construction in progress	55,574	39,835
Total cost	55,574	39,835
Owned Properties | Princeton, New Jersey
Real Estate Properties [Line Items]
Land	20,700	20,700
Buildings, Improvements and Equipment	34,371	34,046
Construction in progress	451	431
Total cost	55,522	55,177
Owned Properties | Eemshaven, Netherlands
Real Estate Properties [Line Items]
Construction in progress	32,468
Total cost	32,468
Owned Properties | Phoenix, Arizona
Real Estate Properties [Line Items]
Construction in progress	30,704	29,562
Total cost	30,704	29,562
Owned Properties | Groningen, Netherlands
Real Estate Properties [Line Items]
Land	1,692
Buildings, Improvements and Equipment	8,389
Construction in progress	2,882
Total cost	12,963
Owned Properties | Other
Real Estate Properties [Line Items]
Land	2,213	2,213
Buildings, Improvements and Equipment	35,909	35,720
Construction in progress	2,892	113
Total cost	$ 41,014	$ 38,046
Leased Properties
Real Estate Properties [Line Items]
Number of facilities leased | facility	9	10
Leased Properties | Owned Properties
Real Estate Properties [Line Items]
Buildings, Improvements and Equipment	$ 98,176	$ 43,347
Construction in progress	1,112	9,334
Total cost	$ 99,288	$ 52,681