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, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Earnings per Share [Abstract]
Net income available to common stockholders - basic	$ 6,507	$ 5,730	$ 15,424	$ 16,719
Effect of net income attributable to noncontrolling interests and income allocated to participating securities	684	808	1,496	2,485
Net income available to common stockholders	$ 7,191	$ 6,538	$ 16,920	$ 19,204
Effect of Class A and Class RS partnership units	6,669	6,767	6,744	6,787
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	1,066	799	982
Basic net income per share	$ 0.13	$ 0.12	$ 0.31	$ 0.37
Diluted net income per share	$ 0.13	$ 0.12	$ 0.31	$ 0.36