Related Party Transactions (Details) (USD $)	1 Months Ended	3 Months Ended				12 Months Ended		3 Months Ended
	Sep. 30, 2011	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2012 Tel(x) [Member] contract sqft	Mar. 31, 2011 Tel(x) [Member]	Dec. 31, 2011 Tel(x) [Member] contract sqft	Sep. 30, 2011 Unrelated Third Party [Member] sqft	Mar. 31, 2012 SoftLayer [Member]	Mar. 31, 2011 SoftLayer [Member]	Mar. 31, 2012 Minimum [Member] SoftLayer [Member]	Mar. 31, 2012 Maximum [Member] SoftLayer [Member]
Related Party Transaction [Line Items]
Number of leases agreement	1			10				9
Lease expiration, date		2026								2013	2025
Terms of lease extended through		2046
Rental revenues		$ 222,834,000	$ 196,795,000	$ 10,400,000	$ 8,800,000			$ 7,300,000	$ 2,300,000
Square footage of net rentable space				254,364		254,314	50
Lease agreements				42		41
Percentage rent lease revenue earned				$ 300,000	$ 100,000
Percentage of rent for management fee		1.00%
Number of lease agreements for the current period								8
Number of lease agreements for future period								1
Lease option extension date										2018	2035