Revenue Recognition - 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
	Dec. 31, 2019	Dec. 31, 2018
Disaggregation Of Revenue [Line Items]
Total revenue	$ 9,083	$ 10,459
Operating Segments
Disaggregation Of Revenue [Line Items]
Total revenue	9,083	10,459
Operating Segments | Oil and Gas Markets
Disaggregation Of Revenue [Line Items]
Total revenue	2,914	3,758
Operating Segments | Oil and Gas Markets | Traditional Exploration Product Revenue
Disaggregation Of Revenue [Line Items]
Total revenue	2,330	2,726
Operating Segments | Oil and Gas Markets | Wireless Exploration Product Revenue
Disaggregation Of Revenue [Line Items]
Total revenue	404	144
Operating Segments | Oil and Gas Markets | Reservoir Product Revenue
Disaggregation Of Revenue [Line Items]
Total revenue	180	888
Operating Segments | Adjacent Markets
Disaggregation Of Revenue [Line Items]
Total revenue	6,072	6,613
Operating Segments | Adjacent Markets | Industrial Product Revenue
Disaggregation Of Revenue [Line Items]
Total revenue	3,596	3,562
Operating Segments | Adjacent Markets | Imaging Product Revenue
Disaggregation Of Revenue [Line Items]
Total revenue	2,476	3,051
Operating Segments | Emerging Markets
Disaggregation Of Revenue [Line Items]
Total revenue	$ 97	$ 88