Quarterly Financial Information (Summary of Selected Quarterly Information) (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
Effect of Fourth Quarter Events [Line Items]
Revenues	$ 112,337	$ 112,213	$ 112,277	$ 113,697	$ 118,911	$ 113,767	$ 107,868	$ 105,964	$ 450,524	$ 446,510	$ 402,363
Operating income (loss)	12,876	(1,552)	1,882	5,455	7,553	12,833	10,826	10,915	18,661	42,127	38,057
Net income (loss)	6,402	(6,892)	(6,433)	(252)	(16,113)	7,394	4,608	5,568	(7,175)	1,457	24,685
Net income (loss) attributable to QTS Realty Trust, Inc.	6,476	(5,282)	(5,431)	(223)	(14,142)	6,507	4,040	4,877	(4,460)	1,282	21,525
Net income (loss) attributable to common stockholders	$ (569)	$ (12,327)	$ (7,679)	$ (551)	$ (14,142)	$ 6,507	$ 4,040	$ 4,877	$ (21,126)	$ 1,282	$ 21,525
Basic (in dollars 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 (in dollars per share)	$ (0.02)	$ (0.25)	$ (0.16)	$ (0.02)	$ (0.29)	$ 0.13	$ 0.08	$ 0.10	$ (0.44)	$ 0.01	$ 0.46
Qualitytech, LP
Effect of Fourth Quarter Events [Line Items]
Revenues	$ 112,337	$ 112,213	$ 112,277	$ 113,697	$ 118,911	$ 113,767	$ 107,868	$ 105,964	$ 450,524	$ 446,510	$ 402,363
Operating income (loss)	12,876	(1,552)	1,882	5,455	7,553	12,833	10,826	10,915	18,661	42,127	38,057
Net income (loss)	6,402	(6,892)	(6,433)	(252)	(16,113)	7,394	4,608	5,568	(7,175)	1,457	24,685
Net income (loss) attributable to common stockholders	$ (643)	$ (13,937)	$ (8,681)	$ (580)	$ (16,113)	$ 7,394	$ 4,608	$ 5,568	$ (23,841)	$ 1,457	$ 24,685