Stockholders' Equity - Change in AOCL (Details) $ in Thousands	6 Months Ended
	Mar. 31, 2021 USD ($)
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	$ 15,443
Balance	134,833
Interest rate caps
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	(3,003)
Other comprehensive income (loss) before reclassification, net of tax	(69)
Reclassification to net earnings, net of tax	244
Balance	(2,828)
Foreign exchange contracts
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	411
Other comprehensive income (loss) before reclassification, net of tax	(601)
Reclassification to net earnings, net of tax	(419)
Balance	(609)
Foreign currency translation adjustments
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	(102,111)
Other comprehensive income (loss) before reclassification, net of tax	17,117
Balance	(84,994)
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	(104,703)
Other comprehensive income (loss) before reclassification, net of tax	16,447
Reclassification to net earnings, net of tax	(175)
Balance	$ (88,431)