BUSINESS SEGMENT AND GEOGRAPHIC INFORMATION - Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Reconciliation of segment operating income to income from continuing operations before income taxes
Segment operating income (loss)									$ 148,349	$ (87,352)	$ 68,200
Income from asset sales									22,660	20,627	9,896
Acquisition related costs									(8,153)
Corporate general and administrative costs and corporate depreciation									(131,254)	(105,816)	(104,062)
Operating income (loss) from continuing operations	$ 23,118	$ 6,217	$ (1,253)	$ 3,520	$ (29,677)	$ (28,028)	$ (65,672)	$ (49,164)	31,602	(172,541)	(25,966)
Other income (expense)
Interest and dividend income									8,017	5,915	3,166
Interest expense									(24,265)	(19,747)	(22,913)
Loss on investment securities									1		(25,989)
Other									486	1,775	(965)
Total other income (expense)									(15,761)	(12,057)	(46,701)
Income (loss) from continuing operations before income taxes									$ 15,841	$ (184,598)	$ (72,667)