Earnings per share of QTS Realty Trust, Inc. (Computation of Basic and Diluted Net Income per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Earnings per Share [Abstract]
Net income (loss)	$ 21,148	$ (252)
Loss (Income) attributable to noncontrolling interests	(1,590)	29
Preferred stock dividends	(7,045)	(328)
Earnings attributable to participating securities	(1,935)	(258)
Net income (loss) available to common stockholders after allocation of participating securities	$ 10,578	$ (809)
Weighted average shares outstanding - basic	51,948	50,279
Effect of Class O units and options to purchase Class A common stock and restricted Class A common stock on an "as if" converted basis	347
Weighted average shares outstanding - diluted	52,295	50,279
Basic net income (loss) per share	$ 0.20	$ (0.02)
Diluted net income (loss) per share	$ 0.20	$ (0.02)