Partners' Capital, Equity and Incentive Compensation Plans (Narrative) (Details)										1 Months Ended	12 Months Ended
	Feb. 18, 2020	Jan. 15, 2020 $ / shares	May 08, 2019 shares	Oct. 15, 2018 $ / shares	Jun. 25, 2018	Apr. 16, 2018 $ / shares	Mar. 15, 2018	May 04, 2017 USD ($) item shares	May 04, 2015 shares	Mar. 31, 2019	Dec. 31, 2019 USD ($) Partnership item shares	Dec. 31, 2017 USD ($)	May 09, 2019 shares	May 03, 2015 shares
Partners Capital And Distributions [Line Items]
Number of classes of partnership units outstanding | Partnership											4
Vesting percentage											8.375%
Equity based compensation expense unrecognized | $											$ 17,000,000.0
Equity based compensation expense vesting period											1 year 1 month 6 days
Preferred Stock, Dividend Rate, Percentage							7.125%
Proceeds net of fees from common equity offering | $											$ 158,663,000	$ 107,495,000
Subsequent Event
Partners Capital And Distributions [Line Items]
Dividends payable, date payable	Apr. 07, 2020
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 | $											$ 35,400,000
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]
Shares reserved for purchase under plan								239,989
Discount rate of purchase price of common stock								10.00%
Series A Redeemable Perpetual Preferred
Partners Capital And Distributions [Line Items]
Preferred stock dividends per share cash paid | $ / shares						$ 0.14844
Series A Redeemable Perpetual Preferred | Subsequent Event
Partners Capital And Distributions [Line Items]
Dividend paid to common stockholders | $ / shares		$ 0.45
Dividends payable, date payable		Jan. 15, 2020
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%
Series B Convertible preferred stock [Member] | Subsequent Event
Partners Capital And Distributions [Line Items]
Dividend paid to common stockholders | $ / shares		$ 1.63
Dividends payable, date payable		Jan. 15, 2020
Preferred Units Series A [Member] | Subsequent Event
Partners Capital And Distributions [Line Items]
Dividend paid to common stockholders | $ / shares		$ 0.45
Preferred Units Series B [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
Holding period after purchase of share								1 year
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]
Options outstanding											600,000
Performance-Based FFO Units
Partners Capital And Distributions [Line Items]
Nonvested awards 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
Nonvested awards 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%
2013 Equity Incentive Plan | Class A Common Stock
Partners Capital And Distributions [Line Items]
Authorized shares to be issued under the plan													5,860,000	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	$ 107,495,000
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%