Shareholders' Equity - Additional Information (Detail) $ / shares in Units, shares in Thousands		1 Months Ended	12 Months Ended
	Oct. 31, 2020 USD ($)	May 31, 2020 USD ($) shares	Sep. 30, 2022 USD ($) $ / shares shares	Sep. 30, 2021 USD ($) agreement shares	Sep. 30, 2020 USD ($)	Nov. 30, 2021 shares	May 01, 2020 shares	Sep. 24, 2013 shares
Class of Stock [Line Items]
Stock Repurchase Program, Number of Shares Authorized to be Repurchased								10,000
Stock Repurchase Program, Number of Additional Shares Authorized to be Repurchased						10,000
Other comprehensive loss before reclassifications, net of taxes | $			$ 306,000,000	$ 383,000,000	$ (338,000,000)
Accelerated Share Repurchase Program
Class of Stock [Line Items]
Total Shares to be Delivered Under Accelerated Share Repurchase Program			1,953
Stock Repurchase Program, Authorized Amount | $			$ 500,000,000	$ 1,250,000,000
Number of Transactions | agreement				2
Treasury Stock, Shares, Acquired			462	4,577
Open Market Repurchases
Class of Stock [Line Items]
Treasury Stock, Shares, Acquired				2,066
Treasury Stock
Class of Stock [Line Items]
Treasury Stock, Value, Acquired, Cost Method | $			$ 650,000,000	$ 1,600,000,000
Treasury Stock, Shares, Acquired			2,415	6,643
Treasury Stock | Accelerated Share Repurchase Program
Class of Stock [Line Items]
Treasury Stock, Value, Acquired, Cost Method | $			$ 150,000,000	$ 1,100,000,000
Treasury Stock | Open Market Repurchases
Class of Stock [Line Items]
Treasury Stock, Value, Acquired, Cost Method | $				500,000,000
Benefit Plans
Class of Stock [Line Items]
Other comprehensive loss before reclassifications, net of taxes | $	$ 24,000,000		$ 169,000,000	$ 187,000,000	$ (101,000,000)
Minimum
Class of Stock [Line Items]
Convertible Preferred Stock, Shares Issued upon Conversion			5,300
Maximum
Class of Stock [Line Items]
Convertible Preferred Stock, Shares Issued upon Conversion			6,400
Convertible Preferred Stock
Class of Stock [Line Items]
Preferred Stock, Shares Outstanding							2,475
Stock Issued During Period, Shares, New Issues		1,500
Gross Proceeds from Issuance of Equity | $		$ 1,500,000,000
Preferred Stock, Depositary Share Ownership Interest, Percentage		5.00%
Proceeds from Issuance of Preferred Stock and Preference Stock | $		$ 1,459,000,000
Preferred Stock, Dividend Rate, Percentage			6.00%
Preferred Stock, Liquidation Preference Per Share | $ / shares			$ 1,000
Depositary Share Liquidation | $			$ 50
Common Stock  Issued at Par Value
Class of Stock [Line Items]
Convertible Preferred Stock, Shares Issued upon Conversion							11,703
Stock Issued During Period, Shares, New Issues		6,250
Gross Proceeds from Issuance of Equity | $		$ 1,500,000,000
Proceeds from Issuance of Preferred Stock and Preference Stock | $		$ 1,459,000,000