CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Data center revenue:
Interconnection revenue	$ 75,751	$ 69,709	$ 62,293
Total operating revenues	572,727	544,392	481,821
Operating expenses:
Property operating and maintenance	157,293	152,357	132,820
Real estate taxes and insurance	22,866	19,239	14,913
Depreciation and amortization	152,925	141,633	129,251
Sales and marketing	22,439	21,023	18,176
General and administrative	43,764	40,090	37,548
Rent	32,624	27,696	24,125
Transaction costs		75	176
Total operating expenses	431,911	402,113	357,009
Operating income	140,816	142,279	124,812
Interest expense	(41,712)	(35,526)	(24,147)
Income before income taxes	99,104	106,753	100,665
Income tax (expense) benefit	(67)	10	(174)
Net income	99,037	106,763	100,491
Net income attributable to noncontrolling interests	23,197	28,841	25,636
Net income attributable to CoreSite Realty Corporation	75,840	77,922	74,855
Preferred stock dividends			(7,924)
Original issuance costs associated with redeemed preferred stock			(4,326)
Net income attributable to common shares	$ 75,840	$ 77,922	$ 62,605
Net income per share attributable to common shares:
Basic	$ 2.06	$ 2.23	$ 1.85
Diluted	$ 2.05	$ 2.22	$ 1.84
Weighted average common shares outstanding
Basic	36,766,310	34,957,244	33,792,759
Diluted	36,943,873	35,137,495	34,058,949
Rental, power, and related revenue
Data center revenue:
Rental revenue	$ 485,131	$ 463,086	$ 407,680
Office, light-industrial and other revenue
Data center revenue:
Rental revenue	$ 11,845	$ 11,597	$ 11,848