Income Taxes - Unremitted Earnings of Foreign Subsidiaries (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2023 USD ($)	Sep. 30, 2023 USD ($)
Deferred Tax Liability Not Recognized, Undistributed Earnings of Foreign Subsidiaries [Abstract]
Outside basis differences in subsidiaries	$ 6,058	$ 6,058
Amount of foreign exchange losses on future repatriation		8,100
Amount of benefit offset by state income taxes, net of the federal benefit		2,000
Amount of foreign cash planned for repatriation	450,000
Unremitted earnings of foreign subsidiaries	$ 1,300,000	$ 1,300,000