STOCK-BASED COMPENSATION - Stock options (Details) - Stock options - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Weighted-average assumptions utilized in determining the fair value of options
Risk-free interest rate (as a percent)				2.20%
Expected stock volatility (as a percent)				36.10%
Dividend yield (as a percent)				4.80%
Expected term (in years)				6 years
Options
Options outstanding at the beginning of the period (in shares)	3,299	3,499	3,499
Exercised (in shares)	(7)		(198)
Forfeited/Expired (in shares)			(9)
Option outstanding at the end of the period (in shares)	3,292	3,299	3,292
Options vested and expected to vest at the end of the period (in shares)	3,292		3,292
Exercisable at the end of the period (in shares)	2,503		2,503
Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 60.74	$ 58.62	$ 58.62
Exercised (in dollars per share)	42.56		22.80
Forfeited/Expired (in dollars per share)			58.43
Outstanding at the end of the period (in dollars per share)	60.77	$ 60.74	60.77
Vested and expected to vest at the end of the period (in dollars per share)	60.77		60.77
Exercisable at the end of the period (in dollars per share)	$ 60.28		$ 60.28
Stock-Based Compensation
Outstanding at the end of the period (in years)			5 years 8 months 12 days
Vested and expected to vest (in years)			5 years 8 months 12 days
Exercisable at the end of the period (in years)	4 years 11 months 5 days
Outstanding at the end of the period, Aggregate Intrinsic Value (in dollars)	$ 5,782.0		$ 5,782.0
Vested and expected to vest at end of the period, Aggregate Intrinsic Value (in dollars)	5,782.0		5,782.0
Exercisable at end of the period, Aggregate Intrinsic Value (in dollars)	$ 5,690.0		$ 5,690.0