Accumulated stock holders' Deficit - Change in AOCL (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	$ (268,556)	$ (363,616)
Balance	(60,323)	(268,556)
Interest rate caps
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	1,365	(1,084)
Other comprehensive income (loss) before reclassifications, net of tax	(6,167)	2,449
Reclassification to net earnings, net of tax	1,601
Balance	(3,201)	1,365
Foreign exchange contracts
Accumulated Other Comprehensive Income Loss [Line Items]
Other comprehensive income (loss) before reclassifications, net of tax	(869)
Reclassification to net earnings, net of tax	715
Balance	(154)
Foreign currency translation adjustments
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	(91,356)	(80,752)
Other comprehensive income (loss) before reclassifications, net of tax	(22,576)	(10,604)
Balance	(113,932)	(91,356)
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	(89,991)	(81,836)
Other comprehensive income (loss) before reclassifications, net of tax	(29,612)	(8,155)
Reclassification to net earnings, net of tax	2,316
Balance	$ (117,287)	$ (89,991)