Business Restructuring Charges - Summary of Restructuring Accrual Activity (Detail) $ in Millions	3 Months Ended
	Dec. 31, 2021 USD ($)
Restructuring Reserve [Roll Forward]
Balance at September 30, 2021	$ 19
Charged to expense	17
Cash payments	(20)
Balance at December 31, 2021	16
Employee Severance [Member]
Restructuring Reserve [Roll Forward]
Balance at September 30, 2021	14
Charged to expense	3
Cash payments	(6)
Balance at December 31, 2021	11
Other Restructuring
Restructuring Reserve [Roll Forward]
Balance at September 30, 2021	5
Charged to expense	14
Cash payments	(14)
Balance at December 31, 2021	$ 5