Reclassifications out of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 2,370,410	$ 2,383,711
Other comprehensive (loss) income before reclassification	(79,800)	40,300
Amounts reclassified from accumulated other comprehensive income (loss)	(2,300)	(3,500)
Ending balance	2,399,543	2,428,218
Accumulated Other Comprehensive Loss
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(882,671)	(926,577)
Ending balance	(964,794)	(889,788)
Pension Related Adjustments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(252,000)	(226,000)
Other comprehensive (loss) income before reclassification	13,800	(9,100)
Amounts reclassified from accumulated other comprehensive income (loss)	500	100
Ending balance	(237,700)	(235,000)
Foreign Currency Translation Adjustments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(646,500)	(739,700)
Other comprehensive (loss) income before reclassification	(105,500)	60,000
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Ending balance	(752,000)	(679,700)
Gain/(Loss) on Derivative Instruments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	15,800	39,100
Other comprehensive (loss) income before reclassification	11,900	(10,600)
Amounts reclassified from accumulated other comprehensive income (loss)	(2,800)	(3,600)
Ending balance	$ 24,900	$ 24,900