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		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings per Share [Abstract]
Net income (loss)	$ (6,892)	$ 7,394	$ (13,577)	$ 17,570
Loss (Income) attributable to noncontrolling interests	1,610	(887)	2,641	(2,146)
Preferred stock dividends	(7,045)		(9,621)
Earnings attributable to participating securities	(206)	(203)	(743)	(650)
Net income (loss) available to common stockholders after allocation of participating securities	$ (12,533)	$ 6,304	$ (21,300)	$ 14,774
Weighted average shares outstanding-basic	50,469	48,714	50,401	47,862
Effect of Class A partnership units		6,669		6,744
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		788		799
Weighted average shares outstanding-diluted	50,469	56,171	50,401	55,405
Basic net income (loss) per share	$ (0.25)	$ 0.13	$ (0.42)	$ 0.31
Diluted net income (loss) per share	$ (0.25)	$ 0.13	$ (0.42)	$ 0.31