Partners' Capital, Equity and Incentive Compensation Plans (Narrative) (Details) $ / shares in Units, $ in Thousands				3 Months Ended								12 Months Ended
	Feb. 20, 2018 $ / shares	Jan. 05, 2018 $ / shares	May 04, 2017 item $ / shares	Dec. 31, 2017 USD ($) item $ / shares shares	Sep. 30, 2017 $ / shares	Jun. 30, 2017 $ / shares	Mar. 31, 2017 USD ($) $ / shares	Dec. 31, 2016 $ / shares	Sep. 30, 2016 $ / shares	Jun. 30, 2016 $ / shares	Mar. 31, 2016 $ / shares	Dec. 31, 2017 USD ($) Partnership item $ / shares shares	Dec. 31, 2016 USD ($) $ / shares	Dec. 31, 2015 USD ($)	May 31, 2015 shares
Partners Capital And Distributions [Line Items]
Equity based compensation expense unrecognized | $				$ 18,100								$ 18,100
Equity based compensation expense vesting period												1 year
Equity based compensation awards intrinsic value | $				$ 59,600								$ 59,600
Dividend paid to common stockholders | $ / shares				$ 0.39	$ 0.39	$ 0.39	$ 0.36	$ 0.36	$ 0.36	$ 0.36	$ 0.32	$ 1.53	$ 1.40
Dividends payable, date payable					Jul. 06, 2017	Apr. 05, 2017	Jan. 05, 2017	Oct. 05, 2016	Jul. 06, 2016	Apr. 05, 2016	Jan. 06, 2016	Oct. 05, 2017
Shares issued, Value | $												$ 107,495	$ 275,862	$ 368,664
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
Dividends payable, date payable	Apr. 05, 2018	Jan. 05, 2018
Dividends payable, date declared	Feb. 20, 2018
Cash dividend payable per common share | $ / shares	$ 0.41
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 | $												$ 108,100
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												2,036,121
Weighted average price per share (in dollars per share) | $ / shares												$ 53.88
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]
Number of classes of partnership units outstanding | Partnership												2
Shares issued, Value | $												$ 107,495	$ 275,862	$ 368,664
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