Reclassifications out of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021
Accumulated balances
Balance at the beginning of the period			$ (900,377)
Balance at the end of the period	$ (864,087)		(864,087)
Pension Related Adjustments
Accumulated balances
Balance at the beginning of the period	(313,400)	$ (353,500)	(316,200)	$ (342,800)
Other comprehensive income (loss) before reclassification	6,500	(3,000)	6,800	(16,700)
Amounts reclassified from accumulated other comprehensive (loss) income	2,500	3,000	5,000	6,000
Balance at the end of the period	(304,400)	(353,500)	(304,400)	(353,500)
Foreign Currency Translation Adjustments
Accumulated balances
Balance at the beginning of the period	(585,300)	(515,600)	(580,100)	(567,300)
Other comprehensive income (loss) before reclassification	(10,400)	(20,000)	(15,600)	31,700
Amounts reclassified from accumulated other comprehensive (loss) income	19,500		19,500
Balance at the end of the period	(576,200)	(535,600)	(576,200)	(535,600)
(Loss)/Gain on Derivative Instruments
Accumulated balances
Balance at the beginning of the period	(500)	(7,700)	(4,100)	(8,600)
Other comprehensive income (loss) before reclassification	16,100	200	18,800	200
Amounts reclassified from accumulated other comprehensive (loss) income	900	900	1,800	1,800
Balance at the end of the period	16,500	(6,600)	16,500	(6,600)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Accumulated balances
Balance at the beginning of the period	(899,200)	(876,800)	(900,400)	(918,700)
Other comprehensive income (loss) before reclassification	12,200	(22,800)	10,000	15,200
Amounts reclassified from accumulated other comprehensive (loss) income	22,900	3,900	26,300	7,800
Balance at the end of the period	$ (864,100)	$ (895,700)	$ (864,100)	$ (895,700)