Employee Benefit Plans - Additional Information (Detail) $ in Millions	3 Months Ended
	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2019 Plan
Defined Benefit Plan Disclosure [Line Items]
Number of foreign defined benefit plans | Plan			1
Pre-tax gain from net pension obligations		$ 6
Additional charge on defined benefit plan actuarial gain (loss)		$ 3
U.S. Defined Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan termination settlements expected future loss	$ 13