Goodwill and Intangible Assets - Goodwill (Details) $ in Thousands	3 Months Ended
	Dec. 31, 2023 USD ($)
Goodwill
Balance at beginning of the period	$ 1,880,244
Translation adjustments	42,902
Balance at end of the period	1,923,146
GSG
Goodwill
Balance at beginning of the period	659,942
Translation adjustments	2,731
Balance at end of the period	662,673
CIG
Goodwill
Balance at beginning of the period	1,220,302
Translation adjustments	40,171
Balance at end of the period	$ 1,260,473