Capital Stock - Additional Information (Detail) - USD ($)	6 Months Ended	12 Months Ended
	Mar. 31, 2023	Sep. 30, 2022	May 05, 2022
Class Of Stock [Line Items]
Number of shares available for repurchase	$ 311,000,000.0
Common Class A [Member]
Class Of Stock [Line Items]
Stock repurchase program, shares repurchased	352,760	1,607,664
Average price	$ 21.23	$ 19.58
Reacquisition cost	$ 7,500,000	$ 31,500,000
Common Class A [Member] | Accelerated Share Repurchase Agreement [Member]
Class Of Stock [Line Items]
Stock repurchase program, shares repurchased		2,508,906
Average price		$ 19.93
Reacquisition cost		$ 50,000,000
Common Class A [Member] | Maximum [Member]
Class Of Stock [Line Items]
Stock repurchase program, authorized amount			$ 400,000,000