Stockholder's Equity (Deficit) - Change in AOCL (Details) $ in Thousands	6 Months Ended
	Mar. 31, 2020 USD ($)
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	$ (60,323)
Balance	(53,195)
Interest rate caps
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	(3,201)
Other comprehensive loss before reclassification, net of tax	(209)
Reclassification to net earnings, net of tax	238
Balance	(3,172)
Foreign exchange contracts
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	(154)
Other comprehensive loss before reclassification, net of tax	(399)
Reclassification to net earnings, net of tax	2,237
Balance	1,684
Foreign currency translation adjustments
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	(113,932)
Other comprehensive loss before reclassification, net of tax	(8,823)
Balance	(122,755)
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	(117,287)
Other comprehensive loss before reclassification, net of tax	(9,431)
Reclassification to net earnings, net of tax	2,475
Balance	$ (124,243)