Schedule II - Valuation and Qualifying Accounts (Details) - Allowance for Doubtful Accounts - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Movement in Valuation Allowances and Reserves
Balance at beginning of year	$ 4,052	$ 3,946	$ 5,599
Charged to costs and expenses	17,970	8,030	7,760
Other	(12,262)	(7,924)	(9,413)
Balance at end of year	$ 9,760	$ 4,052	$ 3,946