Partners' Capital, Equity and Incentive Compensation Plans (Narrative) (Details)											1 Months Ended	3 Months Ended	4 Months Ended	9 Months Ended
	Oct. 15, 2019 $ / shares	Oct. 04, 2019 $ / shares	May 09, 2019 shares	Jun. 25, 2018	Jun. 22, 2018	Apr. 16, 2018 $ / shares	Mar. 15, 2018	May 04, 2017 USD ($) item shares	May 04, 2015 shares	Oct. 13, 2013 Vote shares	Mar. 31, 2019	Mar. 31, 2019 USD ($)	Oct. 31, 2018 $ / shares	Sep. 30, 2019 USD ($) class shares
Partners Capital And Distributions [Line Items]
Number of classes of partnership units outstanding | class														4
Equity based compensation expense unrecognized | $														$ 21,100,000
Equity based compensation expense vesting period														1 year 3 months 18 days
Preferred stock dividends per share cash paid | $ / shares						$ 0.14844
Partnership distribution per unit | $ / shares		$ 0.44
Preferred Stock, Dividend Rate, Percentage							7.125%
Proceeds net of fees from common equity offering | $												$ 158,663,000
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 O Units
Partners Capital And Distributions [Line Items]
Equity based compensation awards intrinsic value | $														$ 30,000,000.0
Class B Common Stock
Partners Capital And Distributions [Line Items]
Number of votes per share | Vote										50
Class A Common Stock | 2017 Plan
Partners Capital And Distributions [Line Items]
Shares reserved for purchase under plan								239,989
Discount rate of purchase price of common stock								10.00%
Series A Redeemable Perpetual Preferred | Subsequent Event
Partners Capital And Distributions [Line Items]
Dividend paid to common stockholders | $ / shares	$ 0.45
Series B Convertible preferred stock [Member]
Partners Capital And Distributions [Line Items]
Preferred stock dividends per share cash paid | $ / shares													$ 1.9861111
Preferred Stock, Dividend Rate, Percentage				6.50%	6.50%
Series B Convertible preferred stock [Member] | Subsequent Event
Partners Capital And Distributions [Line Items]
Dividend paid to common stockholders | $ / shares	1.63
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 shares | $								$ 20
Maximum | 2017 Plan
Partners Capital And Distributions [Line Items]
Deductions per paycheck for purchase of shares | $								$ 1,000
Restricted Class A Common Stock
Partners Capital And Distributions [Line Items]
Nonvested awards outstanding														600,000
Performance-Based FFO Units
Partners Capital And Distributions [Line Items]
Options outstanding														84,350
Performance-Based FFO Units | Minimum | Class A Common Stock
Partners Capital And Distributions [Line Items]
Percentage of target award											0.00%
Performance-Based FFO Units | Maximum | Class A Common Stock
Partners Capital And Distributions [Line Items]
Percentage of target award											200.00%
Performance-Based Relative TSR Units
Partners Capital And Distributions [Line Items]
Vesting period											3 years
Options outstanding														84,350
Performance-Based Relative TSR Units | Minimum | Class A Common Stock
Partners Capital And Distributions [Line Items]
Percentage of target award											0.00%
Performance-Based Relative TSR Units | Maximum | Class A Common Stock
Partners Capital And Distributions [Line Items]
Percentage of target award											200.00%
Options to purchase Class A common stock
Partners Capital And Distributions [Line Items]
Options outstanding														700,000
Equity based compensation awards intrinsic value | $														$ 30,000,000
2013 Equity Incentive Plan | Class A Common Stock
Partners Capital And Distributions [Line Items]
Authorized shares to be issued under the plan										1,750,000
Additional shares available for issuance under plan approved by stockholders			1,110,000						3,000,000
Qualitytech, LP
Partners Capital And Distributions [Line Items]
Proceeds net of fees from common equity offering | $												$ 158,663,000
Qualitytech, LP | Series A Redeemable Perpetual Preferred | Subsequent Event
Partners Capital And Distributions [Line Items]
Dividend paid to common stockholders | $ / shares	$ 0.45
First portion | Performance-Based FFO Units
Partners Capital And Distributions [Line Items]
Vesting period											2 years
Vesting percentage											67.00%
Second portion | Performance-Based FFO Units
Partners Capital And Distributions [Line Items]
Vesting period											3 years
Vesting percentage											33.00%