CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Parenthetical) - $ / shares	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Statement Of Stockholders Equity [Abstract]
Dividends declared on common stock (in dollars per share)	$ 2.49	$ 2.37	$ 2.25
Dividends declared on preferred stock (in dollars per depositary share)	$ 1.84375	$ 0.344