Partners' Capital, Equity and Incentive Compensation Plans (Narrative) (Details)																	1 Months Ended	3 Months Ended	12 Months Ended
	Jan. 15, 2021 $ / shares	Jan. 07, 2021 $ / shares	Sep. 18, 2020 $ / shares	Jun. 19, 2020 $ / shares	Mar. 20, 2020 $ / shares	Dec. 20, 2019 $ / shares	Sep. 19, 2019 $ / shares	Jun. 25, 2019 $ / shares	May 08, 2019 shares	Mar. 20, 2019 $ / shares	Dec. 21, 2018 $ / shares	Jun. 25, 2018 $ / shares shares	Jun. 22, 2018	Mar. 15, 2018 $ / shares shares	May 04, 2017 USD ($) item shares	May 04, 2015 shares	Mar. 31, 2019	Mar. 31, 2019 shares	Dec. 31, 2020 USD ($) Partnership item $ / shares shares	Dec. 31, 2019 USD ($) shares	Dec. 31, 2018 USD ($)	Jun. 30, 2020 $ / shares shares	May 31, 2020 USD ($)	Jun. 30, 2019 USD ($) $ / shares	May 09, 2019 shares	Feb. 28, 2019 $ / shares 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 | $																			$ 26,500,000
Equity based compensation expense vesting period																			10 months 24 days
Dividend rate (as a percent)														7.125%
Proceeds from issuance or sale of equity | $																			$ (286,300,000)
Common stock issuance proceeds, net of costs | $																			$ 285,352,000	$ 268,259,000	$ 0
Preferred stock, liquidation preference (in dollars per share) | $ / shares														$ 25.00
Preferred stock, shares issued (in shares) | shares														4,280,000
At Market
Partners Capital And Distributions [Line Items]
Initial forward sale price per share, calculation value																			100.00%
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
Employee stock purchase plan number of purchase period per year | item															4
Common stock
Partners Capital And Distributions [Line Items]
Dividend paid to common stockholders (in dollars per share) | $ / shares			$ 0.47	$ 0.47	$ 0.47	$ 0.44	$ 0.44	$ 0.44		$ 0.44	$ 0.41
Shares issued | shares																				4,000,000
Common stock | Underwritten Offering
Partners Capital And Distributions [Line Items]
Share Price | $ / shares																						$ 64.90
Common stock | Subsequent Event
Partners Capital And Distributions [Line Items]
Dividend paid to common stockholders (in dollars per share) | $ / shares		$ 0.47
Class O Units
Partners Capital And Distributions [Line Items]
Equity based compensation awards intrinsic value | $																			$ 48,300,000
Class B Common Stock
Partners Capital And Distributions [Line Items]
Number of votes per share | item																			50
Class A Common Stock | Underwritten Offering
Partners Capital And Distributions [Line Items]
Shares issued | shares																		4,000,000
Common stock, shares authorized (in shares) | shares																										7,762,500
Shares to be issued on a forward basis (in shares) | shares																										3,762,500
Common stock, par value (in dollars per share) | $ / shares																										$ 0.01
Class A Common Stock | Prior At Market Offering Program
Partners Capital And Distributions [Line Items]
Maximum value of stock which may be issued | $																								$ 400,000,000
Common stock, par value (in dollars per share) | $ / shares																								$ 0.01
Class A Common Stock | At Market
Partners Capital And Distributions [Line Items]
Maximum value of stock which may be issued | $																							$ 500,000,000
Class A Common Stock | 2017 Plan
Partners Capital And Distributions [Line Items]
Shares reserved for purchase under plan | shares															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, liquidation preference (in dollars per share) | $ / shares																			$ 25.00
Preferred stock redemption price per share | $ / shares																			$ 25.00
Threshold period of redemption of preferred stock																			120 days
Ownership interest																			50.00%
Convertible preferred stock par value | $ / shares																			$ 0.01
Share cap price | $ / shares																			1.46929
Series A Redeemable Perpetual Preferred | Underwriter's Option
Partners Capital And Distributions [Line Items]
Preferred stock, shares issued (in shares) | shares														280,000
Series A Redeemable Perpetual Preferred | Subsequent Event
Partners Capital And Distributions [Line Items]
Dividend paid to common stockholders (in dollars per share) | $ / shares	$ 0.45
Series B Convertible preferred stock
Partners Capital And Distributions [Line Items]
Dividend rate (as a percent)												6.50%
Preferred stock, liquidation preference (in dollars per share) | $ / shares												$ 100.00
Preferred stock, shares issued (in shares) | shares												3,162,500
Share cap price | $ / shares																			$ 5.1020
Minimum percentage of closing sale price of common stock under preferred stock conversion (as a percent)																			150.00%
Maximum trading days of closing sale price of common stock under preferred stock conversion including the last trading day (in days)																			30 days
Period of average daily volume weighted average price																			10 days
Series B Convertible preferred stock | Underwriter's Option
Partners Capital And Distributions [Line Items]
Preferred stock, shares issued (in shares) | shares												412,500
Series B Convertible preferred stock | Subsequent Event
Partners Capital And Distributions [Line Items]
Dividend paid to common stockholders (in dollars per share) | $ / shares	$ 1.63
Series B Convertible preferred stock
Partners Capital And Distributions [Line Items]
Dividend rate (as a percent)													6.50%
Minimum trading days of closing sale price of common stock under preferred stock conversion (in days)																			20 days
Maximum trading days of closing sale price of common stock under preferred stock conversion including the last trading day (in days)																			30 days
Conversion of stock, conversion rate																			2.1404
Preferred Units Series A | QualityTech, LP
Partners Capital And Distributions [Line Items]
Conversion ratio, stock for cash or stock																			1
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															500.00%
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
Maximum | Common stock | Underwritten Offering
Partners Capital And Distributions [Line Items]
Common stock, shares authorized (in shares) | shares																						4,400,000
Restricted Class A Common Stock
Partners Capital And Distributions [Line Items]
Options outstanding | shares																			100,000
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%
2013 Equity Incentive Plan | Class A Common Stock
Partners Capital And Distributions [Line Items]
Authorized shares to be issued under the plan | shares																									5,900,000		1,750,000
Additional shares available for issuance under plan approved by stockholders | shares									1,100,000							3,000,000.0
Second portion | Performance-Based FFO Units
Partners Capital And Distributions [Line Items]
Vesting period																	3 years