CAPITAL STOCK - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Jun. 12, 2024	Sep. 30, 2023	May 05, 2022
Class Of Stock [Line Items]
Reacquisition cost	$ 50,400	$ 48,480	$ 176,616	$ 55,968
Number of shares available for repurchase	$ 625,300		$ 625,300		$ 76,000
Common Class A
Class Of Stock [Line Items]
Common stock, par value (in dollars per share)	$ 0.001		$ 0.001			$ 0.001
Treasury stock purchases (in shares)	857,000	1,947,000	4,110,000	2,300,000
Shares acquired, average cost per share (in dollars per share)	$ 47.14	$ 24.90	$ 40.54	$ 24.34
Reacquisition cost	$ 50,400	$ 48,480	$ 176,615	$ 55,968
Stock repurchase program, authorized amount					$ 600,000
Common Class A | Secondary Offerings
Class Of Stock [Line Items]
Treasury stock purchases (in shares)		1,477,832
Shares acquired, average cost per share (in dollars per share)		$ 24.36
Reacquisition cost		$ 36,000		$ 36,000
Common Class A | Secondary Offerings - Sold By Stockholders
Class Of Stock [Line Items]
Sale of stock, number of shares issued (in shares)		16,100,000
Common stock, par value (in dollars per share)		$ 0.001		$ 0.001
Sales price per share (in dollars per share)		$ 24.36		$ 24.36
Stock issuance costs		$ 1,100
Common Class A | Over-Allotment Option - Sold By Stockholders
Class Of Stock [Line Items]
Sale of stock, number of shares issued (in shares)		2,100,000
Common Class A | Maximum
Class Of Stock [Line Items]
Stock repurchase program, authorized amount							$ 400,000