Partners' Capital, Equity and Incentive Compensation Plans (Narrative) (Details) $ / shares in Units, $ in Thousands			3 Months Ended						9 Months Ended
	Oct. 05, 2017 $ / shares	May 04, 2017 item $ / shares	Sep. 30, 2017 USD ($) item $ / shares shares	Jun. 30, 2017 $ / shares	Mar. 31, 2017 USD ($) $ / shares	Sep. 30, 2016 $ / shares	Jun. 30, 2016 $ / shares	Mar. 31, 2016 $ / shares	Sep. 30, 2017 USD ($) security item $ / shares shares	May 31, 2015 shares
Partners Capital And Distributions [Line Items]
Number of classes of partnership units outstanding | security									2
Equity based compensation expense unrecognized | $			$ 21,700						$ 21,700
Equity based compensation expense vesting period									1 year 1 month 6 days
Equity based compensation awards intrinsic value | $			$ 59,600						$ 59,600
Dividend paid to common stockholders | $ / shares			$ 0.39	$ 0.39	$ 0.36	$ 0.36	$ 0.36	$ 0.32
Dividends payable, date payable			Jul. 06, 2017	Apr. 05, 2017	Jan. 05, 2017	Jul. 06, 2016	Apr. 05, 2016	Jan. 06, 2016
Shares issued, Value | $									$ 92,587
QTS Realty Trust, Inc. Employee Stock Purchase Plan
Partners Capital And Distributions [Line Items]
Shares reserved for purchase under plan | shares			250,000						250,000
2017 Plan
Partners Capital And Distributions [Line Items]
Minimum period of service		30 days
Minimum hours per week of service | item		30
Purchase period per year | item		4
Subsequent Event
Partners Capital And Distributions [Line Items]
Dividend paid to common stockholders | $ / shares	$ 0.39
Partnership distribution per unit | $ / shares	$ 0.39
Dividends payable, date payable	Oct. 05, 2017
Class RS Units
Partners Capital And Distributions [Line Items]
Number of units outstanding | shares			0						0
Class B Common Stock
Partners Capital And Distributions [Line Items]
Number of votes per share | item			50						50
Class A Common Stock
Partners Capital And Distributions [Line Items]
Net proceeds from issuance of shares | $			$ 54,000						$ 93,000
Class A Common Stock | At Market [Member]
Partners Capital And Distributions [Line Items]
Maximum value of stock which may be issued | $					$ 300,000
Shares issued | shares			1,015,332						1,761,681
Weighted average price per share (in dollars per share) | $ / shares			$ 53.65						$ 53.63
Class A Common Stock | 2017 Plan
Partners Capital And Distributions [Line Items]
Discount rate of purchase price of common stock		10.00%
Chief Executive Officer | Class B Common Stock
Partners Capital And Distributions [Line Items]
Percentage of operating partnership unit exchanged									2.00%
Qualitytech, LP
Partners Capital And Distributions [Line Items]
Shares issued, Value | $									$ 92,587
Minimum | 2017 Plan
Partners Capital And Distributions [Line Items]
Minimum percentage of combined voting power		5.00%
Deductions per paycheck for purchase of share | $ / shares		$ 20
Holding period after purchase of share		1 year
Maximum | 2017 Plan
Partners Capital And Distributions [Line Items]
Deductions per paycheck for purchase of share | $ / shares		$ 1,000
Restricted Class A Common Stock
Partners Capital And Distributions [Line Items]
Nonvested awards outstanding | shares			400,000						400,000
Options to purchase Class A common stock
Partners Capital And Distributions [Line Items]
Nonvested awards outstanding | shares			600,000						600,000
2013 Equity Incentive Plan
Partners Capital And Distributions [Line Items]
Authorized shares to be issued under the plan | shares			1,750,000						1,750,000	4,750,000