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, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings per Share [Abstract]
Net income (loss)	$ 6,588	$ 7,535	$ 21,148	$ (6,892)	$ (6,433)	$ (252)	$ 35,271	$ (13,577)
Loss (Income) attributable to noncontrolling interests	49			1,610			(1,593)	2,641
Preferred stock dividends	(7,045)			(7,045)			(21,135)	(9,621)
Earnings attributable to participating securities	(2,184)			(206)			(5,999)	(743)
Net income (loss) available to common stockholders after allocation of participating securities	$ (2,592)			$ (12,533)			$ 6,544	$ (21,300)
Weighted average shares outstanding - basic	54,928			50,469			53,874	50,401
Effect of Class O units, TSR units and options to purchase Class A common stock on an "as if" converted basis							463
Weighted average shares outstanding - diluted	54,928			50,469			54,337	50,401
Basic net income (loss) per share	$ (0.05)			$ (0.25)			$ 0.12	$ (0.42)
Diluted net income (loss) per share	$ (0.05)			$ (0.25)			$ 0.12	$ (0.42)