Quarterly Financial Information (Summary of Selected Quarterly Information) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Effect of Fourth Quarter Events [Line Items]
Revenues	$ 123,707	$ 125,255	$ 119,167	$ 112,689	$ 112,337	$ 112,213	$ 112,277	$ 113,697	$ 480,818	$ 450,524	$ 446,510
Operating income (loss)	4,218	13,606	14,598	28,734	12,876	(1,552)	1,882	5,455	61,156	18,661	42,127
Net income (loss)	(3,606)	6,588	7,535	21,148	6,402	(6,892)	(6,433)	(252)	31,665	(7,175)	1,457
Net income (loss) attributable to QTS Realty Trust, Inc.	(2,511)	6,637	7,483	19,558	6,476	(5,282)	(5,431)	(223)	31,291	(4,460)	1,282
Net income (loss) attributable to common stockholders	$ (9,556)	$ (408)	$ 438	$ 12,513	$ (569)	$ (12,327)	$ (7,679)	$ (551)	$ 3,111	$ (21,126)	$ 1,282
Basic (in dollars per share)	$ (0.20)	$ (0.05)	$ (0.03)	$ 0.20	$ (0.02)	$ (0.25)	$ (0.16)	$ (0.02)	$ (0.09)	$ (0.44)	$ 0.01
Diluted (in dollars per share)	$ (0.20)	$ (0.05)	$ (0.03)	$ 0.20	$ (0.02)	$ (0.25)	$ (0.16)	$ (0.02)	$ (0.09)	$ (0.44)	$ 0.01
Qualitytech, LP
Effect of Fourth Quarter Events [Line Items]
Revenues	$ 123,707	$ 125,255	$ 119,167	$ 112,689	$ 112,337	$ 112,213	$ 112,277	$ 113,697	$ 480,818	$ 450,524	$ 446,510
Operating income (loss)	4,218	13,606	14,598	28,734	12,876	(1,552)	1,882	5,455	61,156	18,661	42,127
Net income (loss)	(3,606)	6,588	7,535	21,148	6,402	(6,892)	(6,433)	(252)	31,665	(7,175)	1,457
Net income (loss) attributable to common stockholders	$ (10,651)	$ (457)	$ 490	$ 14,103	$ (643)	$ (13,937)	$ (8,681)	$ (580)	$ 3,485	$ (23,841)	$ 1,457