CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Data center revenue:
Rental revenue	$ 131,080	$ 116,146	$ 101,449
Power revenue	59,663	53,672	43,661
Interconnection revenue	28,932	21,637	12,677
Tenant reimbursement and other	7,317	7,088	6,610
Office, light industrial and other revenue	7,841	8,391	8,449
Total operating revenues	234,833	206,934	172,846
Operating expenses:
Property operating and maintenance	64,260	61,235	55,049
Real estate taxes and insurance	8,458	8,765	9,119
Depreciation and amortization	65,785	64,327	68,967
Sales and marketing	14,405	10,330	5,744
General and administrative	27,317	25,910	21,846
Rent	19,659	18,711	18,336
Transaction costs	279	613	875
Total operating expenses	200,163	189,891	179,936
Operating income (loss)	34,670	17,043	(7,090)
Gain on early extinguishment of debt			939
Interest income	32	13	117
Interest expense	(2,689)	(5,236)	(5,275)
Income (loss) before income taxes	32,013	11,820	(11,309)
Income tax (expense) benefit	(401)	(1,104)	530
Net income (loss)	31,612	10,716	(10,779)
Net income (loss) attributable to noncontrolling interests	12,771	5,668	(6,168)
Net income (loss) attributable to CoreSite Realty Corporation	18,841	5,048	(4,611)
Preferred stock dividends	(8,338)	(440)
Net income(loss) attributable to common shares	$ 10,503	$ 4,608	$ (4,611)
Net income (loss) per share attributable to common shares:
Basic (in dollars per share)	$ 0.50	$ 0.22	$ (0.24)
Diluted (in dollars per share)	$ 0.49	$ 0.22	$ (0.24)
Weighted average common shares outstanding
Basic (in shares)	20,826,622	20,537,946	19,609,375
Diluted (in shares)	21,503,212	20,992,290	19,609,375