Supplementary Balance Sheet Information - Valuation Allowance for Deferred Tax Assets Activity (Details) - Valuation Allowance of Deferred Tax Assets - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation Allowances and Reserves, Balance, Beginning Balance	$ 92,297	$ 104,802	$ 18,797
Charged to Provisions	(72,842)	(10,881)	77,531
Charged to Other Accounts	(874)	(1,624)	8,474
Valuation Allowances and Reserves, Balance, Ending Balance	$ 18,581	$ 92,297	$ 104,802