Accounts Receivable (Allowance for Doubtful Accounts Rollforward) (Details) $ in Thousands	12 Months Ended
	Sep. 30, 2018 USD ($) customers	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of period	$ 22	$ 36	$ 462
Provision adjustment - expense, net of recoveries	599	23	23
Write-offs and other adjustments - deductions to receivable balances	(73)	(37)	(449)
Balance at end of period	548	22	36
Reserve on accounts receivable	$ 599	$ 23	$ 23
Number of customer account balances determined uncertain for collectability | customers	2
Customer Accounts With Uncertainty For Total Collectability
Allowance for Doubtful Accounts Receivable [Roll Forward]
Reserve on accounts receivable	$ 500