Equity Items - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions		1 Months Ended			3 Months Ended				6 Months Ended
	Mar. 31, 2022	Apr. 30, 2023	Mar. 31, 2023	Feb. 28, 2023	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2023	Mar. 31, 2022	Sep. 30, 2022	Mar. 01, 2022
Accelerated Share Repurchases [Line Items]
Accrued expenses and other liabilities			$ 206		$ 206				$ 206		$ 269
Common shares repurchased					1,488,251		2,403,380		1,488,251	2,403,380
Dividend per common share					$ 0.335	$ 0.335	$ 0.300	$ 0.300
2022 Stock Repurchase Program [Member]
Accelerated Share Repurchases [Line Items]
Stock repurchase during period value			52	$ 100
Aggregate amount of common stock to be repurchased			100	$ 100	$ 100				$ 100
Cash settled			42
Accrued expenses and other liabilities			$ 10		$ 10				$ 10
Stock repurchased and retired during period shares			500,000	1,000,000.0
2022 Stock Repurchase Program [Member] | Subsequent Event [Member]
Accelerated Share Repurchases [Line Items]
Stock repurchase during period value		$ 100
Stock repurchased and retired during period shares		1,000,000.0
2018 Stock Repurchase Program [Member]
Accelerated Share Repurchases [Line Items]
Stock repurchase during period value	$ 155
Aggregate amount of common stock to be repurchased												$ 200
Stock repurchased and retired during period shares	1,700,000