Accounts Receivable (Allowance for Doubtful Accounts Rollforward) (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2018 USD ($) customers	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) customers	Jun. 30, 2017 USD ($)
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of period	$ 95	$ 13	$ 22	$ 36
Provision adjustment - expense, net of recoveries	524	0	599	7
Write-offs and other adjustments - deductions to receivable balances	(21)	(6)	(23)	(36)
Balance at end of period	598	$ 7	598	7
Reserve on accounts receivable	$ 500		$ 599	$ 7
Number of customer account balances determined uncertain for collectability | customers	2		2