Real Estate Assets and Construction in Progress - Summary of Properties Owned or Leased by the Company (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Real Estate Properties [Line Items]
Land	$ 30,601	$ 30,601
Buildings and improvements	743,101	728,230
Construction in progress	182,699	146,904
Total Cost	956,401	905,735
Owned Properties [Member]
Real Estate Properties [Line Items]
Land	30,601	30,601
Buildings and improvements	717,636	703,657
Construction in progress	182,699	146,904
Total Cost	930,936	881,162
Owned Properties [Member] | Suwanee, Georgia (Atlanta-Suwanee) [Member]
Real Estate Properties [Line Items]
Land	3,521	3,521
Buildings and improvements	127,143	126,486
Construction in progress	4,513	3,270
Total Cost	135,177	133,277
Owned Properties [Member] | Atlanta, Georgia (Atlanta-Metro) [Member]
Real Estate Properties [Line Items]
Land	15,397	15,397
Buildings and improvements	308,935	296,547
Construction in progress	37,432	32,456
Total Cost	361,764	344,400
Owned Properties [Member] | Santa Clara, California [Member]
Real Estate Properties [Line Items]
Buildings and improvements	87,415	86,544
Construction in progress	1,276	1,249
Total Cost	88,691	87,793
Owned Properties [Member] | Richmond, Virginia [Member]
Real Estate Properties [Line Items]
Land	2,180	2,180
Buildings and improvements	109,018	108,979
Construction in progress	69,958	67,155
Total Cost	181,156	178,314
Owned Properties [Member] | Sacramento, California [Member]
Real Estate Properties [Line Items]
Land	1,481	1,481
Buildings and improvements	52,975	52,841
Construction in progress	4,484	4,273
Total Cost	58,940	58,595
Owned Properties [Member] | Dallas, Texas [Member]
Real Estate Properties [Line Items]
Land	5,808	5,808
Construction in progress	65,036	38,501
Total Cost	70,844	44,309
Owned Properties [Member] | Miami, Florida [Member]
Real Estate Properties [Line Items]
Land	1,777	1,777
Buildings and improvements	27,569	27,553
Total Cost	29,346	29,330
Owned Properties [Member] | Lenexa, Kansas [Member]
Real Estate Properties [Line Items]
Land	437	437
Buildings and improvements	3,172	3,298
Total Cost	3,609	3,735
Owned Properties [Member] | Wichita, Kansas [Member]
Real Estate Properties [Line Items]
Buildings and improvements	1,409	1,409
Total Cost	1,409	1,409
Leased Properties [Member]
Real Estate Properties [Line Items]
Buildings and improvements	25,465	24,573
Total Cost	25,465	24,573
Leased Properties [Member] | Jersey City, New Jersey [Member]
Real Estate Properties [Line Items]
Buildings and improvements	24,689	23,811
Total Cost	24,689	23,811
Leased Properties [Member] | Overland Park, Kansas [Member]
Real Estate Properties [Line Items]
Buildings and improvements	776	762
Total Cost	$ 776	$ 762