LONG-TERM DEBT - Letter of Credit Facilities (Details) - USD ($) $ in Millions	Sep. 30, 2019	Sep. 30, 2018	Feb. 21, 2014
Standby Letters of Credit
Debt Instrument [Line Items]
Maximum limit on issuance of letters of credit			$ 25
Amount outstanding, letters of credit	$ 1
Other Letters of Credit Arrangements
Debt Instrument [Line Items]
Amount outstanding, letters of credit	$ 12	$ 19