Stockholders' Equity and Weighted Average Common Shares Outstanding - Components of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Sep. 30, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	$ (1,018,924)	$ 2,878,917
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	(108,830)	(111,965)
Pension and postretirement adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	(5,761)	(5,344)
Foreign currency translation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	(103,043)	(107,252)
Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	$ (26)	$ 631