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, 2020	Mar. 31, 2019
Earnings per Share [Abstract]
Net income	$ 8,120	$ 21,148
Income attributable to noncontrolling interests	(110)	(1,590)
Preferred stock dividends	(7,045)	(7,045)
Earnings attributable to participating securities	(1,596)	(1,935)
Net income (loss) available to common stockholders after allocation of participating securities	$ (631)	$ 10,578
Weighted average shares outstanding - basic	58,038	51,948
Effect of Class O units, TSR units and options to purchase Class A common stock on an "as if" converted basis		347
Weighted average shares outstanding - diluted	58,038	52,295
Basic net income (loss) per share	$ (0.01)	$ 0.20
Diluted net income (loss) per share	$ (0.01)	$ 0.20