Trade Accounts Receivable and Financing Receivables - Financing Receivables (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Sep. 30, 2019
Accounts Notes And Loans Receivable [Line Items]
Total financing receivables	$ 2,661	$ 3,472
Total unearned income	(28)	(55)
Total financing receivables, net of unearned income	2,633	3,417
Less current portion	(2,517)	(3,233)
Non-current financing receivables	116	184
Promissory Notes
Accounts Notes And Loans Receivable [Line Items]
Total financing receivables	607	780
Sales Type Lease
Accounts Notes And Loans Receivable [Line Items]
Total financing receivables	2,054	2,692
Total unearned income	$ (28)	$ (55)