v3.21.2
Pension and Other Postretirement Benefits - Pension Plan Assets (Detail) - USD ($)
$ in Millions
Sep. 30, 2021
Sep. 30, 2020
Sep. 30, 2019
U.S. Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets $ 1,288 $ 1,142 $ 1,090
U.S. Plans | Fair Value, Measurements, Recurring      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 1,288 1,142  
U.S. Plans | Fair Value, Measurements, Recurring | Cash and cash equivalents      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 20 17  
U.S. Plans | Fair Value, Measurements, Recurring | Collective investment funds      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 548 509  
U.S. Plans | Fair Value, Measurements, Recurring | Corporate debt securities      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 455 373  
U.S. Plans | Fair Value, Measurements, Recurring | U.S. government-sponsored debt securities      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 28 30  
U.S. Plans | Fair Value, Measurements, Recurring | U.S. Treasury securities      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 105 84  
U.S. Plans | Fair Value, Measurements, Recurring | Asset-backed securities      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 31 37  
U.S. Plans | Fair Value, Measurements, Recurring | Equity securities      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 101 92  
U.S. Plans | Fair Value, Measurements, Recurring | Level 1      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 226 193  
U.S. Plans | Fair Value, Measurements, Recurring | Level 1 | Cash and cash equivalents      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 20 17  
U.S. Plans | Fair Value, Measurements, Recurring | Level 1 | Collective investment funds      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 0 0  
U.S. Plans | Fair Value, Measurements, Recurring | Level 1 | Corporate debt securities      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 0 0  
U.S. Plans | Fair Value, Measurements, Recurring | Level 1 | U.S. government-sponsored debt securities      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 0 0  
U.S. Plans | Fair Value, Measurements, Recurring | Level 1 | U.S. Treasury securities      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 105 84  
U.S. Plans | Fair Value, Measurements, Recurring | Level 1 | Asset-backed securities      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 0 0  
U.S. Plans | Fair Value, Measurements, Recurring | Level 1 | Equity securities      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 101 92  
U.S. Plans | Fair Value, Measurements, Recurring | Level 2      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 1,031 912  
U.S. Plans | Fair Value, Measurements, Recurring | Level 2 | Cash and cash equivalents      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 0 0  
U.S. Plans | Fair Value, Measurements, Recurring | Level 2 | Collective investment funds      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 548 509  
U.S. Plans | Fair Value, Measurements, Recurring | Level 2 | Corporate debt securities      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 455 373  
U.S. Plans | Fair Value, Measurements, Recurring | Level 2 | U.S. government-sponsored debt securities      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 28 30  
U.S. Plans | Fair Value, Measurements, Recurring | Level 2 | U.S. Treasury securities      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 0 0  
U.S. Plans | Fair Value, Measurements, Recurring | Level 2 | Asset-backed securities      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 0 0  
U.S. Plans | Fair Value, Measurements, Recurring | Level 2 | Equity securities      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 0 0  
U.S. Plans | Fair Value, Measurements, Recurring | Level 3      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 31 37  
U.S. Plans | Fair Value, Measurements, Recurring | Level 3 | Cash and cash equivalents      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 0 0  
U.S. Plans | Fair Value, Measurements, Recurring | Level 3 | Collective investment funds      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 0 0  
U.S. Plans | Fair Value, Measurements, Recurring | Level 3 | Corporate debt securities      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 0 0  
U.S. Plans | Fair Value, Measurements, Recurring | Level 3 | U.S. government-sponsored debt securities      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 0 0  
U.S. Plans | Fair Value, Measurements, Recurring | Level 3 | U.S. Treasury securities      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 0 0  
U.S. Plans | Fair Value, Measurements, Recurring | Level 3 | Asset-backed securities      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 31 37  
U.S. Plans | Fair Value, Measurements, Recurring | Level 3 | Equity securities      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 0 0  
Non-U.S. Plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 548 525 $ 490
Non-U.S. Plans | Fair Value, Measurements, Recurring      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 548 525  
Non-U.S. Plans | Fair Value, Measurements, Recurring | Cash and cash equivalents      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 18 6  
Non-U.S. Plans | Fair Value, Measurements, Recurring | Corporate debt securities      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 51 48  
Non-U.S. Plans | Fair Value, Measurements, Recurring | Asset-backed securities      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 78 67  
Non-U.S. Plans | Fair Value, Measurements, Recurring | Equity funds      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 68 65  
Non-U.S. Plans | Fair Value, Measurements, Recurring | Multi-asset securities      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 333 339  
Non-U.S. Plans | Fair Value, Measurements, Recurring | Level 1      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 18 6  
Non-U.S. Plans | Fair Value, Measurements, Recurring | Level 1 | Cash and cash equivalents      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 18 6  
Non-U.S. Plans | Fair Value, Measurements, Recurring | Level 1 | Corporate debt securities      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 0 0  
Non-U.S. Plans | Fair Value, Measurements, Recurring | Level 1 | Asset-backed securities      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 0 0  
Non-U.S. Plans | Fair Value, Measurements, Recurring | Level 1 | Equity funds      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 0 0  
Non-U.S. Plans | Fair Value, Measurements, Recurring | Level 1 | Multi-asset securities      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 0 0  
Non-U.S. Plans | Fair Value, Measurements, Recurring | Level 2      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 452 452  
Non-U.S. Plans | Fair Value, Measurements, Recurring | Level 2 | Cash and cash equivalents      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 0 0  
Non-U.S. Plans | Fair Value, Measurements, Recurring | Level 2 | Corporate debt securities      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 51 48  
Non-U.S. Plans | Fair Value, Measurements, Recurring | Level 2 | Asset-backed securities      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 0 0  
Non-U.S. Plans | Fair Value, Measurements, Recurring | Level 2 | Equity funds      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 68 65  
Non-U.S. Plans | Fair Value, Measurements, Recurring | Level 2 | Multi-asset securities      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 333 339  
Non-U.S. Plans | Fair Value, Measurements, Recurring | Level 3      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 78 67  
Non-U.S. Plans | Fair Value, Measurements, Recurring | Level 3 | Cash and cash equivalents      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 0 0  
Non-U.S. Plans | Fair Value, Measurements, Recurring | Level 3 | Corporate debt securities      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 0 0  
Non-U.S. Plans | Fair Value, Measurements, Recurring | Level 3 | Asset-backed securities      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 78 67  
Non-U.S. Plans | Fair Value, Measurements, Recurring | Level 3 | Equity funds      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets 0 0  
Non-U.S. Plans | Fair Value, Measurements, Recurring | Level 3 | Multi-asset securities      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Fair value of plan assets $ 0 $ 0