CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Parenthetical) - $ / shares	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Statement Of Stockholders Equity [Abstract]
Dividends declared on common stock (in dollars per share)	$ 0.65	$ 0.6225	$ 1.30	$ 1.245
Dividends declared on preferred stock (in dollars per depositary share)	$ 0.36875	$ 0.36875	$ 0.7375	$ 1.10625