Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Accounts receivable, allowance for doubtful accounts	$ 1,490	$ 1,037
Preferred shares, par (in usd per share)	$ 0.01	$ 0.01
Preferred shares, authorized (in shares)	2,000,000	2,000,000
Cumulative convertible perpetual preferred shares, dividend rate	7.25%	7.25%
Cumulative convertible perpetual preferred shares, liquidation preference (in usd per share)	$ 50	$ 50
Cumulative convertible perpetual preferred shares, issued (in shares)	1,849,000	1,849,000
Cumulative convertible perpetual preferred shares, outstanding (in shares)	1,849,000	1,849,000
Common shares of beneficial interest, par (in usd per share)	$ 0.01	$ 0.01
Common shares of beneficial interest, authorized (in shares)	240,000,000	120,000,000
Common shares of beneficial interest, issued (in shares)	79,969,000	79,850,000
Common shares of beneficial interest, outstanding (in shares)	79,969,000	79,850,000