Summary of Revenue from the Sale of Products and Performance of Services Under Contracts with Customers Excludes All Revenue Earned from Rental Contracts by Operating Segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation Of Revenue [Line Items]
Total revenue	$ 12,153	$ 13,270	$ 34,457	$ 40,454
Operating Segments
Disaggregation Of Revenue [Line Items]
Total revenue	12,153	13,270	34,457	40,454
Operating Segments | Oil and Gas Markets
Disaggregation Of Revenue [Line Items]
Total revenue	3,931	4,516	12,254	17,464
Operating Segments | Oil and Gas Markets | Traditional Exploration Product Revenue
Disaggregation Of Revenue [Line Items]
Total revenue	2,129	2,424	8,116	8,513
Operating Segments | Oil and Gas Markets | Wireless Exploration Product Revenue
Disaggregation Of Revenue [Line Items]
Total revenue	1,381	273	1,835	4,454
Operating Segments | Oil and Gas Markets | Reservoir Product Revenue
Disaggregation Of Revenue [Line Items]
Total revenue	421	1,819	2,303	4,497
Operating Segments | Adjacent Markets
Disaggregation Of Revenue [Line Items]
Total revenue	8,211	8,754	22,058	22,990
Operating Segments | Adjacent Markets | Industrial Product Revenue
Disaggregation Of Revenue [Line Items]
Total revenue	5,364	5,674	13,046	14,061
Operating Segments | Adjacent Markets | Imaging Product Revenue
Disaggregation Of Revenue [Line Items]
Total revenue	2,847	$ 3,080	9,012	$ 8,929
Operating Segments | Emerging Markets
Disaggregation Of Revenue [Line Items]
Total revenue	$ 11		$ 145