CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDER'S EQUITY (Parenthetical) - $ / shares	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Statement of Stockholders' Equity [Abstract]
Dividends (in dollars per share)	$ 1.74	$ 1.66	$ 1.40
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201802Member	us-gaap:AccountingStandardsUpdate201409Member