Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Trust shares, par value (in dollars per share)
Trust shares, authorized (shares)	500,000,000	500,000,000
Trust shares, issued (shares)	59,900,000	59,900,000
Trust shares, outstanding (shares)	59,900,000	59,900,000
Preferred Stock, Shares Authorized	50,000,000	50,000,000
Accounts Receivable, Allowance for Credit Loss	$ 14,107	$ 14,800
Accumulated Amortization, Debt Issuance Costs, Noncurrent	$ 3,724	$ 3,754
Series A Preferred Stock
Class of Stock [Line Items]
Preferred Stock, No Par Value
Preferred Stock, Shares Issued	4,000,000	4,000,000
Preferred Stock, Shares Outstanding	4,000,000	4,000,000
Series B Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock, No Par Value
Preferred Stock, Shares Issued	4,000,000	4,000,000
Preferred Stock, Shares Outstanding	4,000,000	4,000,000
Series C Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock, No Par Value
Preferred Stock, Shares Issued	4,600,000	4,600,000
Preferred Stock, Shares Outstanding	4,600,000	4,600,000