Partners' Capital, Equity and Incentive Compensation Plans (Narrative) (Details) $ / shares in Units, $ in Millions			6 Months Ended
	Jul. 16, 2018 $ / shares	May 04, 2017 item $ / shares	Jun. 30, 2018 USD ($) item shares	Mar. 31, 2017 USD ($)	May 31, 2015 shares
Partners Capital And Distributions [Line Items]
Number of classes of partnership units outstanding | item			4
Equity based compensation expense unrecognized | $			$ 21.7
Equity based compensation expense vesting period			1 year 3 months 18 days
Equity based compensation awards intrinsic value | $			$ 35.0
QTS Realty Trust, Inc. Employee Stock Purchase Plan
Partners Capital And Distributions [Line Items]
Shares reserved for purchase under plan			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 RS Units
Partners Capital And Distributions [Line Items]
Number of units outstanding			0
Class B Common Stock
Partners Capital And Distributions [Line Items]
Number of votes per share | item			50
Class A Common Stock | At Market
Partners Capital And Distributions [Line Items]
Maximum value of stock which may be issued | $				$ 300.0
Shares issued			0
Class A Common Stock | 2017 Plan
Partners Capital And Distributions [Line Items]
Discount rate of purchase price of common stock		10.00%
Preferred Class A [Member]
Partners Capital And Distributions [Line Items]
Preferred Stock, Dividends, Per Share, Cash Paid | $ / shares	$ 0.45
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			500,000
Options to purchase Class A common stock
Partners Capital And Distributions [Line Items]
Nonvested awards outstanding			900,000
2013 Equity Incentive Plan
Partners Capital And Distributions [Line Items]
Authorized shares to be issued under the plan			1,750,000		4,750,000