Schedule III Real Estate and Accumulated Depreciation (Details) (USD $)	Dec. 31, 2012
Real Estate and Accumulated Depreciation
Encumbrances	$ 59,750,000
Initial Cost
Land	84,737,000
Building and Improvements	371,788,000
Costs Capitalized Subsequent to Acquisition
Land	1,131,000
Building and Improvements	368,467,000
Gross Amount Carried As of Year End
Land	85,868,000
Building and Improvements	740,255,000
Total	826,123,000
Accumulated Depreciation	104,490,000
Aggregate cost of the total properties for federal income tax purposes	812,200,000
SV1, San Jose, CA
Real Estate and Accumulated Depreciation
Encumbrances	59,750,000
Initial Cost
Land	6,863,000
Building and Improvements	91,719,000
Costs Capitalized Subsequent to Acquisition
Building and Improvements	15,023,000
Gross Amount Carried As of Year End
Land	6,863,000
Building and Improvements	106,742,000
Total	113,605,000
Accumulated Depreciation	7,342,000
SV2, Milpitas, CA
Initial Cost
Land	5,086,000
Building and Improvements	5,046,000
Costs Capitalized Subsequent to Acquisition
Building and Improvements	17,502,000
Gross Amount Carried As of Year End
Land	5,086,000
Building and Improvements	22,548,000
Total	27,634,000
Accumulated Depreciation	8,073,000
SV3, Santa Clara, CA
Initial Cost
Land	3,972,000
Building and Improvements	3,482,000
Costs Capitalized Subsequent to Acquisition
Building and Improvements	41,731,000
Gross Amount Carried As of Year End
Land	3,972,000
Building and Improvements	45,213,000
Total	49,185,000
Accumulated Depreciation	11,246,000
SV4, Santa Clara, CA
Initial Cost
Land	4,442,000
Building and Improvements	3,716,000
Costs Capitalized Subsequent to Acquisition
Building and Improvements	79,920,000
Gross Amount Carried As of Year End
Land	4,442,000
Building and Improvements	83,636,000
Total	88,078,000
Accumulated Depreciation	3,136,000
Santa Clara Campus, Santa Clara, CA
Initial Cost
Land	11,486,000
Building and Improvements	9,240,000
Costs Capitalized Subsequent to Acquisition
Land	1,131,000
Building and Improvements	4,088,000
Gross Amount Carried As of Year End
Land	12,617,000
Building and Improvements	13,328,000
Total	25,945,000
Accumulated Depreciation	2,115,000
BO1, Somerville, MA
Initial Cost
Land	6,100,000
Building and Improvements	26,748,000
Costs Capitalized Subsequent to Acquisition
Building and Improvements	43,652,000
Gross Amount Carried As of Year End
Land	6,100,000
Building and Improvements	70,400,000
Total	76,500,000
Accumulated Depreciation	18,682,000
NY1, New York, NY
Costs Capitalized Subsequent to Acquisition
Building and Improvements	31,292,000
Gross Amount Carried As of Year End
Building and Improvements	31,292,000
Total	31,292,000
Accumulated Depreciation	9,199,000
VA1, Reston, VA
Initial Cost
Land	12,100,000
Building and Improvements	32,939,000
Costs Capitalized Subsequent to Acquisition
Building and Improvements	74,783,000
Gross Amount Carried As of Year End
Land	12,100,000
Building and Improvements	107,722,000
Total	119,822,000
Accumulated Depreciation	17,901,000
DC1, Washington, DC
Initial Cost
Building and Improvements	4,797,000
Costs Capitalized Subsequent to Acquisition
Building and Improvements	1,996,000
Gross Amount Carried As of Year End
Building and Improvements	6,793,000
Total	6,793,000
Accumulated Depreciation	1,197,000
CH1, Chicago, IL
Initial Cost
Land	5,493,000
Building and Improvements	49,522,000
Costs Capitalized Subsequent to Acquisition
Building and Improvements	25,921,000
Gross Amount Carried As of Year End
Land	5,493,000
Building and Improvements	75,443,000
Total	80,936,000
Accumulated Depreciation	6,008,000
LA1, Los Angeles, CA
Initial Cost
Building and Improvements	41,099,000
Costs Capitalized Subsequent to Acquisition
Building and Improvements	10,735,000
Gross Amount Carried As of Year End
Building and Improvements	51,834,000
Total	51,834,000
Accumulated Depreciation	8,505,000
LA2, Los Angeles, CA
Initial Cost
Land	28,467,000
Building and Improvements	94,114,000
Costs Capitalized Subsequent to Acquisition
Building and Improvements	21,155,000
Gross Amount Carried As of Year End
Land	28,467,000
Building and Improvements	115,269,000
Total	143,736,000
Accumulated Depreciation	10,102,000
MI1, Miami, FL
Initial Cost
Land	728,000
Building and Improvements	9,325,000
Costs Capitalized Subsequent to Acquisition
Building and Improvements	432,000
Gross Amount Carried As of Year End
Land	728,000
Building and Improvements	9,757,000
Total	10,485,000
Accumulated Depreciation	964,000
DE1, Denver, CO
Initial Cost
Building and Improvements	37,000
Costs Capitalized Subsequent to Acquisition
Building and Improvements	232,000
Gross Amount Carried As of Year End
Building and Improvements	269,000
Total	269,000
Accumulated Depreciation	18,000
DE2, Denver, CO
Initial Cost
Building and Improvements	4,000
Costs Capitalized Subsequent to Acquisition
Building and Improvements	5,000
Gross Amount Carried As of Year End
Building and Improvements	9,000
Total	9,000
Accumulated Depreciation	$ 2,000