CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Operating revenues:
Rental revenue	$ 35,283	$ 31,603	$ 102,590	$ 91,837
Power revenue	15,979	14,230	43,994	39,543
Interconnection revenue	7,441	6,177	21,066	15,268
Tenant reimbursement and other	1,932	1,752	5,743	5,034
Total operating revenues	60,635	53,762	173,393	151,682
Operating expenses:
Property operating and maintenance	17,368	16,360	47,013	46,029
Real estate taxes and insurance	2,226	2,158	6,750	6,304
Depreciation and amortization	16,424	16,583	48,634	47,991
Sales and marketing	3,206	2,231	10,931	6,941
General and administrative	7,045	6,389	20,225	18,777
Rent	5,082	4,689	14,631	13,957
Transaction costs	25	293	279	576
Total operating expenses	51,376	48,703	148,463	140,575
Operating income	9,259	5,059	24,930	11,107
Interest income	14	5	18	12
Interest expense	(708)	(1,595)	(1,930)	(3,922)
Income before income taxes	8,565	3,469	23,018	7,197
Income tax expense	(56)	(522)	(435)	(1,059)
Net income	8,509	2,947	22,583	6,138
Net income attributable to noncontrolling interests	3,524	1,627	8,962	3,389
Net income attributable to CoreSite Realty Corporation	4,985	1,320	13,621	2,749
Preferred stock dividends	(2,084)		(6,253)
Net income attributable to common shares	$ 2,901	$ 1,320	$ 7,368	$ 2,749
Net income per share attributable to common shares:
Basic (in dollars per share)	$ 0.14	$ 0.06	$ 0.35	$ 0.13
Diluted (in dollars per share)	$ 0.14	$ 0.06	$ 0.34	$ 0.13
Weighted average common shares outstanding
Basic (in shares)	20,871,504	20,554,893	20,793,596	20,514,713
Diluted (in shares)	21,479,971	21,027,635	21,465,710	20,890,894