Partners' Capital, Equity and Incentive Compensation Plans (Narrative) (Details) $ / shares in Units, $ in Millions			1 Months Ended	3 Months Ended				6 Months Ended
	Jul. 06, 2017 $ / shares	May 04, 2017 item $ / shares	Mar. 31, 2017 shares	Jun. 30, 2017 USD ($) item $ / shares shares	Mar. 31, 2017 $ / shares	Jun. 30, 2016 $ / shares	Mar. 31, 2016 $ / shares	Jun. 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 | $				$ 25.3				$ 25.3
Equity based compensation expense vesting period								1 year 3 months 18 days
Equity based compensation awards intrinsic value | $				$ 77.7				$ 77.7
Dividend paid to common stockholders | $ / shares				$ 0.39	$ 0.36	$ 0.36	$ 0.32
Dividends payable, date payable				Apr. 05, 2017	Jan. 05, 2017	Apr. 05, 2016	Jan. 06, 2016
QTS Realty Trust, Inc. Employee Stock Purchase Plan [Member]
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 [Member]
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	Jul. 06, 2017
Class RS Units [Member]
Partners Capital And Distributions [Line Items]
Number of units outstanding | shares				0				0
Common Class B [Member]
Partners Capital And Distributions [Line Items]
Number of votes per share | item				50				50
Common Class A [Member]
Partners Capital And Distributions [Line Items]
Shares issued | shares			300,000,000	746,349
Shares issued, price per share | $ / shares				$ 53.60				$ 53.60
Net proceeds from issuance of shares | $				$ 39.0
Common Class A [Member] | 2017 Plan
Partners Capital And Distributions [Line Items]
Discount rate of purchase price of common stock		10.00%
Chief Executive Officer [Member] | Common Class B [Member]
Partners Capital And Distributions [Line Items]
Percentage of operating partnership unit exchanged								2.00%
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 [Member]
Partners Capital And Distributions [Line Items]
Nonvested awards outstanding | shares				500,000				500,000
Options to purchase Class A common stock [Member]
Partners Capital And Distributions [Line Items]
Nonvested awards outstanding | shares				600,000				600,000
2013 Equity Incentive Plan [Member]
Partners Capital And Distributions [Line Items]
Authorized shares to be issued under the plan | shares				1,750,000				1,750,000	4,750,000