Condensed Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common shares Class A Common Stock	Common shares Class B-1 Common Stock	Common shares Class B-2 Common Stock	Additional Paid In Capital	Retained Earnings	Cumulative Other Comprehensive Income	Cumulative Common Distributions	Total Shareholders' Equity	Noncontrolling Interest
Balance beginning at Sep. 30, 2018	$ 434,661	$ 15	$ 1	$ 15	$ 99,239	$ 182,877	$ 82	$ (49,467)	$ 232,762	$ 201,899
Increase (Decrease) in Shareholders' Equity
Share grants, net	1,569				1,569				1,569
Net income	118,080					52,209			52,209	65,871
Tax distributions to Member	(8,037)									(8,037)
Common share distributions	(10,180)							(5,680)	(5,680)	(4,500)
Other comprehensive loss	(4)						(2)		(2)	(2)
Balance ending at Dec. 31, 2018	536,089	15	1	15	100,808	235,086	80	(55,147)	280,858	255,231
Balance beginning at Sep. 30, 2018	434,661	15	1	15	99,239	182,877	82	(49,467)	232,762	201,899
Increase (Decrease) in Shareholders' Equity
Net income	136,788
Balance ending at Mar. 31, 2019	533,778	15	1	15	101,670	243,254	0	(60,827)	284,128	249,650
Balance beginning at Dec. 31, 2018	536,089	15	1	15	100,808	235,086	80	(55,147)	280,858	255,231
Increase (Decrease) in Shareholders' Equity
Share grants, net	862				862				862
Net income	18,708					8,168			8,168	10,540
Tax distributions to Member	(11,616)									(11,616)
Common share distributions	(10,180)							(5,680)	(5,680)	(4,500)
Other comprehensive loss	(10)						(5)		(5)	(5)
Reclassification due to disposition of our Australian operations	(75)						(75)		(75)
Balance ending at Mar. 31, 2019	533,778	15	1	15	101,670	243,254	$ 0	(60,827)	284,128	249,650
Balance beginning at Sep. 30, 2019	529,035	15	1	15	103,360	257,457		(72,194)	288,654	240,381
Increase (Decrease) in Shareholders' Equity
Share grants, net	634				634				634
Net income	21,624					9,449			9,449	12,175
Tax distributions to Member	(3,830)									(3,830)
Common share distributions	(10,695)							(6,195)	(6,195)	(4,500)
Balance ending at Dec. 31, 2019	536,768	15	1	15	103,994	266,906		(78,389)	292,542	244,226
Balance beginning at Sep. 30, 2019	529,035	15	1	15	103,360	257,457		(72,194)	288,654	240,381
Increase (Decrease) in Shareholders' Equity
Net income	36,545
Balance ending at Mar. 31, 2020	538,110	15	1	15	105,265	273,374		(84,583)	294,087	244,023
Balance beginning at Dec. 31, 2019	536,768	15	1	15	103,994	266,906		(78,389)	292,542	244,226
Increase (Decrease) in Shareholders' Equity
Share grants, net	1,271				1,271				1,271
Net income	14,921					6,468			6,468	8,453
Tax distributions to Member	(4,156)									(4,156)
Common share distributions	(10,694)							(6,194)	(6,194)	(4,500)
Balance ending at Mar. 31, 2020	$ 538,110	$ 15	$ 1	$ 15	$ 105,265	$ 273,374		$ (84,583)	$ 294,087	$ 244,023