CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Sep. 30, 2021
Cash flows from operating activities:
Net (loss) income	$ 53,146	$ (107,760)	$ 41,944	$ (20,608)
Adjustments, Noncash Items, to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
Depreciation and amortization	119,930	491,419	150,350	125,642
Reduction in the carrying amount of right-of-use assets	5,915	13,869	7,627	5,515
Net foreign currency losses (gains)		4,079	1,232
Net foreign currency losses (gains)	(306)	4,100		5,525
Net realized loss on settlement of foreign currency forward contracts	0	26,176		0
Stock-based compensation	15,763	84,850	16,131	1,744
Deferred income taxes	(79,021)	(192,926)	(84,713)	(57,086)
Provision for uncollectible receivables	794	7,827	853	(145)
Other non-cash operating activities	228	(228)	(289)	165
Changes in assets and liabilities:
Accounts receivable	11,204	(25,538)	4,486	(5,476)
Contract assets	(78,122)	(21,658)	82,898	(17,868)
Contract costs	(4,992)	(10,165)	4,992	0
Lease liabilities	(5,558)	(13,655)	5,979	(4,673)
Prepaid expenses, prepaid income taxes, and other assets	(8,776)	7,625	6,965	1,553
Accounts payable, accrued expenses, income taxes payable and other liabilities	(23,674)	18,315	(25,908)	(1,740)
Contract liabilities	22,431	16,979	17,291	22,252
Net cash provided by operating activities	28,962	299,209	19,776	54,800
Cash flows from investing activities:
Purchase of property, equipment and leasehold improvements	(2,263)	(6,577)	(4,870)	(6,185)
Proceeds from sale of property and equipment	91	0	91	0
Payments for business acquisitions, net of cash acquired	5,571,931	72,498	5,572,996	1,588,802
Net payments for settlement of foreign currency forward contracts	0	26,176		0
Payments for equity method investments	(24)	(700)	(24)	0
Payments for capitalized computer software development costs	(508)	(366)	508	0
Purchase of other assets	(553)	(1,000)	(838)	(5)
Net cash (used in) investing activities	(5,575,188)	(107,317)	(5,579,145)	(1,594,982)
Cash flows from financing activities:
Issuance of shares of common stock	5,702	36,736	5,702	0
Repurchases of common stock	0	(100,000)		0
Payment of tax withholding obligations related to restricted stock	(1,676)	(20,836)	(1,676)	0
Deferred business acquisition payments	(1,200)	(1,363)	(1,200)	0
Repayments of amounts borrowed under term loan	(6,000)			0
Net transfers (to) from Parent Company	5,971,995	19,933	5,987,190	1,551,537
Payments of debt issuance costs	0	2,375		0
Net cash (used in) provided by financing activities	5,968,821	(383,771)	5,984,016	1,551,537
Effect of exchange rate changes on cash and cash equivalents	1,417	(16,637)	1,419	(141)
(Decrease) increase in cash and cash equivalents	424,012	(208,516)	426,066	11,214
Cash and cash equivalents, beginning of period	25,713	449,725	23,659	14,499
Cash and cash equivalents, end of period	449,725	241,209	$ 449,725	25,713
Supplemental disclosure of cash flow information:
Income taxes paid, net	84,997	79,819		9,600
Interest paid	237	13,615		693
Supplemental disclosure of non-cash activities:
Change in purchases of property, equipment and leasehold improvements included in accounts payable and accrued expenses	(363)	(915)		483
Lease liabilities arising from obtaining right-of-use assets	$ 280	$ 1,345		$ 219