Partners' Capital, Equity and Incentive Compensation Plans (Schedule of Quarterly Cash Dividends) (Details) - USD ($)														1 Months Ended	3 Months Ended	6 Months Ended		12 Months Ended
	Jul. 15, 2020	Jul. 07, 2020	Apr. 15, 2020	Apr. 07, 2020	Jan. 15, 2020	Jan. 07, 2020	Apr. 15, 2019	Apr. 04, 2019	Jan. 15, 2019	Jan. 08, 2019	Jun. 25, 2018	Jun. 22, 2018	Mar. 15, 2018	Jun. 30, 2020	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Dividend rate (as a percent)													7.125%
Preferred stock, shares issued													4,280,000
Preferred stock redemption price per share														$ 25.00		$ 25.00
Threshold period of redemption of preferred stock																120 days
Voting power threshold (as a percent)														50.00%		50.00%
Convertible preferred stock par value														$ 0.01		$ 0.01
Preferred stock, liquidation preference													$ 25.00	25.00		25.00
Share cap price														$ 1.46929		$ 1.46929
Net proceeds																$ 134,077,000	$ 159,026,000
Preferred Units, Issued													4,280,000
Series A Preferred Stock
Record Date			Mar. 31, 2020		Dec. 31, 2019		Mar. 31, 2019		Dec. 31, 2018
Payment Date			Apr. 15, 2020		Jan. 15, 2020		Apr. 15, 2019		Jan. 15, 2019
Per Common Share and Per Unit Rate			$ 0.45		$ 0.45		$ 0.45		$ 0.45
Dividend/Distribution Amount			$ 1,900,000		$ 1,900,000		$ 1,900,000		$ 1,900,000							3,800,000	3,800,000
Series B Preferred Stock
Record Date			Mar. 31, 2020		Dec. 31, 2019		Mar. 31, 2019		Dec. 31, 2018
Payment Date			Apr. 15, 2020		Jan. 15, 2020		Apr. 15, 2019		Jan. 15, 2019
Per Common Share and Per Unit Rate			$ 1.63		$ 1.63		$ 1.63		$ 1.63
Dividend/Distribution Amount			$ 5,100,000		$ 5,100,000		$ 5,100,000		$ 5,100,000							$ 10,200,000	10,300,000
Series A Redeemable Perpetual Preferred Stock
Dividend rate (as a percent)																7.125%		7.125%
Preferred stock, shares issued														4,280,000		4,280,000		4,280,000
Preferred stock, liquidation preference														$ 25.00		$ 25.00		$ 25.00
Series B Convertible Perpetual Preferred Stock
Dividend rate (as a percent)											6.50%	6.50%				6.50%		6.50%
Preferred stock, shares issued											3,162,500			3,162,500		3,162,500		3,162,500
Conversion rate																2.1362
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
Preferred stock, liquidation preference											$ 100.00			$ 100.00		$ 100.00		$ 100.00
Period of average daily volume weighted average price																10 days
Share cap price														$ 5.1020		$ 5.1020
Series B Convertible Perpetual Preferred Stock | Minimum
Minimum percentage of closing sale price of common stock under preferred stock conversion (as a percent)																150.00%
Subsequent Event | Series A Redeemable Perpetual Preferred Stock
Record Date	Jun. 30, 2020
Per Common Share and Per Unit Rate	$ 0.45
Subsequent Event | Series B Convertible Perpetual Preferred Stock
Record Date	Jun. 30, 2020
Per Common Share and Per Unit Rate	$ 1.63
Underwriter's Option
Preferred stock, shares issued													280,000
Underwriter's Option | Series B Convertible Perpetual Preferred Stock
Preferred stock, shares issued											412,500
Qualitytech, LP
Net proceeds																$ 134,077,000	159,026,000
Qualitytech, LP | Series A Redeemable Perpetual Preferred Units
Dividend rate (as a percent)																7.125%		7.125%
Preferred stock, shares issued														4,280,000		4,280,000		4,280,000
Preferred stock, liquidation preference														$ 25.00		$ 25.00		$ 25.00
Qualitytech, LP | Series B Redeemable Perpetual Preferred Units
Dividend rate (as a percent)																6.50%		6.50%
Preferred stock, shares issued														3,162,500		3,162,500		3,162,500
Preferred stock, liquidation preference														$ 100.00		$ 100.00		$ 100.00
Qualitytech, LP | Series B Convertible Perpetual Preferred Stock
Preferred stock, shares issued											3,162,500
Qualitytech, LP | Subsequent Event | Series A Redeemable Perpetual Preferred Units
Dividend/Distribution Amount	$ 0.45
Qualitytech, LP | Subsequent Event | Series B Convertible Perpetual Preferred Stock
Per Common Share and Per Unit Rate	$ 1.63
Common stock
Record Date				Mar. 20, 2020		Dec. 20, 2019		Mar. 20, 2019		Dec. 21, 2018
Payment Date				Apr. 07, 2020		Jan. 07, 2020		Apr. 04, 2019		Jan. 08, 2019
Per Common Share and Per Unit Rate				$ 0.47		$ 0.44		$ 0.44		$ 0.41
Dividend/Distribution Amount				$ 31,500,000		$ 28,600,000		$ 27,300,000		$ 23,700,000						$ 60,100,000	$ 51,000,000.0
Shares issued															4,000,000
Common stock | Subsequent Event
Record Date		Jun. 19, 2020
Per Common Share and Per Unit Rate		$ 0.47
Common stock | Underwritten Offering
Share price														$ 64.90		$ 64.90
Net proceeds														$ 271,900,000