SHAREHOLDERS' EQUITY - Additional Information (Details) - USD ($)	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017	Nov. 07, 2019	Jul. 26, 2019	Jun. 30, 2019	Nov. 02, 2018	Jul. 21, 2016
Class of Stock [Line Items]
Dividends declared or paid	$ 0	$ 0	$ 0
Common stock authorized (in shares)	500,000,000
Common stock par value (in dollars per share)	$ 1
Preferred stock authorized (in shares)	30,000,000
Common stock reserved for issuance under long-term incentive plan (in shares)	13,000,000
Common stock available for future grants under long-term incentive plan (in shares)	2,900,000
Treasury stock acquired during period (in shares)		4,500,000
Repurchase of common stock	$ 96,000,000	$ 100,000,000
Debt Securities
Class of Stock [Line Items]
Remaining authorized stock repurchase amount		$ 50,000,000
Remaining authorized debt repurchase amount						$ 76,000,000
Repurchased principal amount of debt			$ 100,000,000
Series A Junior Preferred Stock
Class of Stock [Line Items]
Preferred stock authorized (in shares)	2,000,000
Preferred stock issued (in shares)	0
Repurchase Program, July 2019 | Common Stock
Class of Stock [Line Items]
Stock repurchase, authorized amount					$ 250,000,000
Common stock repurchased (in shares)	1,300,000
Value of common stock repurchased	$ 25,000,000
Remaining authorized stock repurchase amount	$ 225,000,000
Repurchase Progam, November 2018 | Debt Securities
Class of Stock [Line Items]
Repurchase program, authorized amount							$ 100,000,000
Repurchase Progam, November 2018 | Common Stock
Class of Stock [Line Items]
Stock repurchase, authorized amount							$ 200,000,000
Common stock repurchased (in shares)	4,000,000.0
Value of common stock repurchased	$ 71,000,000
Repurchase Program, July 2016 | Debt Securities
Class of Stock [Line Items]
Repurchase program, authorized amount								$ 150,000,000
Repurchase Program, July 2016 | Common Stock
Class of Stock [Line Items]
Stock repurchase, authorized amount								$ 100,000,000
Subsequent Event | Repurchase Program, November 2019 | Common Stock
Class of Stock [Line Items]
Stock repurchase, authorized amount				$ 325,000,000