Investment in Real Estate (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Investment in Real Estate
Land	$ 78,337	$ 78,983
Buildings and Improvements	1,012,845	888,966
Construction in progress	106,872	$ 178,599
Total investments in real estate	1,198,054
SV1 San Jose CA
Investment in Real Estate
Land	6,863
Buildings and Improvements	127,032
Construction in progress	469
Total investments in real estate	134,364
SV2 Milpitas CA
Investment in Real Estate
Land	5,086
Buildings and Improvements	26,822
Construction in progress	680
Total investments in real estate	32,588
SV3 Santa Clara CA
Investment in Real Estate
Land	3,972
Buildings and Improvements	49,146
Construction in progress	295
Total investments in real estate	53,413
SV4 Santa Clara CA
Investment in Real Estate
Land	4,501
Buildings and Improvements	90,806
Construction in progress	726
Total investments in real estate	96,033
SV5 Santa Clara CA
Investment in Real Estate
Land	2,544
Buildings and Improvements	23,514
Total investments in real estate	26,058
SV6 Santa Clara CA
Investment in Real Estate
Construction in progress	17,142
Total investments in real estate	17,142
Santa Clara Campus Properties Santa Clara CA
Investment in Real Estate
Land	3,518
Buildings and Improvements	2,916
Construction in progress	4,239
Total investments in real estate	10,673
BO1 Somerville MA
Investment in Real Estate
Land	5,154
Buildings and Improvements	81,982
Construction in progress	265
Total investments in real estate	87,401
NY1 New York NY
Investment in Real Estate
Buildings and Improvements	34,369
Construction in progress	8
Total investments in real estate	34,377
NY2 Secaucus NJ
Investment in Real Estate
Land	2,388
Buildings and Improvements	89,075
Construction in progress	36,719
Total investments in real estate	128,182
VA1 Reston VA
Investment in Real Estate
Land	6,903
Buildings and Improvements	114,724
Construction in progress	4,131
Total investments in real estate	125,758
VA2 Reston VA
Investment in Real Estate
Land	2,720
Buildings and Improvements	63,177
Construction in progress	32,105
Total investments in real estate	98,002
DC1 Washington DC
Investment in Real Estate
Buildings and Improvements	7,976
Construction in progress	151
Total investments in real estate	8,127
CH1 Chicago IL
Investment in Real Estate
Land	5,493
Buildings and Improvements	87,109
Construction in progress	5,363
Total investments in real estate	97,965
LA1 Los Angeles CA
Investment in Real Estate
Buildings and Improvements	63,340
Construction in progress	2,514
Total investments in real estate	65,854
LA2 Los Angeles CA
Investment in Real Estate
Land	28,467
Buildings and Improvements	136,684
Construction in progress	1,831
Total investments in real estate	166,982
MI1 Miami FL
Investment in Real Estate
Land	728
Buildings and Improvements	10,332
Construction in progress	2
Total investments in real estate	11,062
DE1 Denver CO
Investment in Real Estate
Buildings and Improvements	2,789
Construction in progress	232
Total investments in real estate	3,021
DE2 Denver CO
Investment in Real Estate
Buildings and Improvements	1,052
Total investments in real estate	$ 1,052