Earnings per share of QTS Realty Trust, Inc. (Computation of Basic and Diluted Net Income per Share) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings per Share [Abstract]
Net income (loss)	$ 6,402	$ (6,892)	$ (6,433)	$ (252)	$ (16,113)	$ 7,394	$ 4,608	$ 5,568	$ (7,175)	$ 1,457	$ 24,685
Loss (Income) attributable to noncontrolling interests									2,715	(175)	(3,160)
Preferred stock dividends									(16,666)
Earnings attributable to participating securities									(947)	(593)	3,160
Net income (loss) available to common stockholders after allocation of participating securities									$ (22,073)	$ 689	$ 24,685
Weighted average shares outstanding-basic									50,432,590	48,380,964	46,205,937
Effect of Class A partnership units										6,696,000	6,783,000
Effect of Class O units and options to purchase Class A common stock on an "as if" converted basis										779,000	973,000
Weighted average shares outstanding-diluted									50,432,590	55,855,683	53,962,234
Basic net income (loss) per share	$ (0.02)	$ (0.25)	$ (0.16)	$ (0.02)	$ (0.29)	$ 0.13	$ 0.08	$ 0.10	$ (0.44)	$ 0.01	$ 0.47
Diluted net income (loss) per share	$ (0.02)	$ (0.25)	$ (0.16)	$ (0.02)	$ (0.29)	$ 0.13	$ 0.08	$ 0.10	$ (0.44)	$ 0.01	$ 0.46