Equity - Class B Preferred Units (Details) - USD ($)							3 Months Ended
	Jan. 15, 2021	Oct. 15, 2020	Jul. 15, 2020	Apr. 15, 2020	Jul. 02, 2019	Jun. 13, 2017	Sep. 30, 2019	Jun. 30, 2019
Preferred Units
Preferred units issued, net of offering costs							$ 102,757,000	$ 42,638,000
Class B Perpetual Preferred Units
Preferred Units
Preferred units dividend rate						9.00%
Preferred unit par or stated value per unit						$ 25.00
Preferred units issued, net of offering costs						$ 202,700,000
Preferred units, underwriting discounts and commissions						6,600,000
Preferred units, offering costs						$ 700,000
Distributions made to preferred unitholders distributions declared per unit		$ 0.5625	$ 0.5625	$ 0.5625
Amount paid to preferred unitholders		$ 7,079,000	$ 7,079,000	$ 7,079,000
Class B Perpetual Preferred Units
Preferred Units
Preferred units, dividend payment terms						The current distribution rate for the Class B Preferred Units is 9.00% per year of the $25.00 liquidation preference per unit (equal to $2.25 per unit per year).
Class B Perpetual Preferred Units | Class B Perpetual Preferred Units
Preferred Units
Preferred units, issued (in units)						8,400,000
Class B Perpetual Preferred Units | Class B Perpetual Preferred Units
Preferred Units
Preferred units, issued (in units)					4,185,642
Subsequent Event | Class B Perpetual Preferred Units
Preferred Units
Distributions made to preferred unitholders distributions declared per unit	$ 0.5625
Amount paid to preferred unitholders	$ 7,079,000