Partners' Capital, Equity and Incentive Compensation Plans (Narrative) (Details) $ / shares in Units, $ in Millions		9 Months Ended
	May 04, 2017 item $ / shares	Sep. 30, 2018 USD ($) item shares	May 31, 2015 shares
Partners Capital And Distributions [Line Items]
Number of classes of partnership units outstanding | item		4
Equity based compensation expense unrecognized | $		$ 17.8
Equity based compensation expense vesting period		1 year 7 months 6 days
Equity based compensation awards intrinsic value | $		$ 38.9
QTS Realty Trust, Inc. Employee Stock Purchase Plan
Partners Capital And Distributions [Line Items]
Shares reserved for purchase under plan | shares		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
Class B Common Stock
Partners Capital And Distributions [Line Items]
Number of votes per share | item		50
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%
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		500,000
Options to purchase Class A common stock
Partners Capital And Distributions [Line Items]
Nonvested awards outstanding | shares		900,000
2013 Equity Incentive Plan
Partners Capital And Distributions [Line Items]
Authorized shares to be issued under the plan | shares		1,750,000	4,750,000