CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended			9 Months Ended
	Dec. 31, 2010	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Sep. 27, 2010 Predecessor
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)	$ (10,722)	$ 10,716	$ (10,779)	$ (9,181)	$ (1,555)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	19,146	64,327	68,967		11,848
Amortization of above/below market leases	(390)	(1,505)	(1,650)		(171)
Amortization of deferred financing costs	427	1,681	1,556		323
Gain on early extinguishment of debt			(939)
Amortization of share-based compensation	538	5,650	2,958
Amortization of discount to fair market value of acquired loan	916		687
Bad debt expense	25	544	292		(82)
Changes in operating assets and liabilities:
Restricted cash	3,670	132	712		(250)
Accounts receivable	(1,790)	(3,657)	(1,523)		583
Due to and due from related parties			2		875
Deferred rent receivable	(995)	(3,966)	(4,986)		(1,656)
Deferred leasing costs	(503)	(4,105)	(4,215)		(4,449)
Other assets	(987)	(2,597)	(1,227)		(253)
Accounts payable and accrued expenses	(176)	2,245	7,273		(317)
Prepaid rent and other liabilities	1,528	(1,611)	2,820		(222)
Deferred rent payable	400	794	1,258		143
Net cash provided by operating activities	11,087	68,648	61,206		4,817
CASH FLOWS FROM INVESTING ACTIVITIES
Tenant improvements	(4,623)	(6,075)	(5,328)		(287)
Real estate improvements	(6,725)	(83,837)	(112,196)		(44,404)
Assumption of cash balances in connection with the contribution of the CoreSite Acquired Properties	10,269
Acquisition of Comfluent, net of cash received		(2,581)
Changes in reserves for capital improvements	50	8,691	4,965		239
Net cash used in investing activities	(1,029)	(83,802)	(112,559)		(44,452)
CASH FLOWS FROM FINANCING ACTIVITIES
Issuance of common stock	310,960
Offering costs	(25,182)		(17)
Proceeds from exercise of stock options		1,564	31
Gross proceeds from issuance of Series A Preferred Stock		115,000
Series A Preferred Stock offering costs paid		(4,190)
Redemption of operating partnership units	(125,513)
Proceeds from revolving credit facility		72,750	5,000
Payments on revolving credit facility		(77,750)
Proceeds from mortgage loans payable	60,000		6,440		10,302
Repayments of mortgage loans payable	(152,600)	(57,114)	(14,189)
Payments of loan fees and costs	(3,440)	(503)	(1,745)		(272)
Reduction in contribution receivables	2,703
Contributions					33,399
Dividends and distributions		(33,101)	(23,785)		(2,000)
Net cash provided by (used in) financing activities	66,928	16,656	(28,265)		41,429
Net change in cash and cash equivalents	76,986	1,502	(79,618)		1,794
Cash and cash equivalents, beginning of period	9,260	6,628	86,246		7,466
Cash and cash equivalents, end of period	86,246	8,130	6,628	86,246	9,260
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION
Cash paid for interest	1,278	5,492	4,360		1,193
NON-CASH INVESTING AND FINANCING ACTIVITY
Construction costs payable capitalized to real estate	2,890	10,520	5,564		1,516
Contribution of the CoreSite Acquired Properties for Operating Partnership units	316,836
Accrual of dividends and distributions	5,967	13,384	8,453	5,967
Accrued offering costs	$ 124