Summary of Revenue from the Sale of Products and Services Under Contracts with Customers Excludes All Revenue Earned from Rental Contracts by Operating Segments (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Disaggregation Of Revenue [Line Items]
Total revenue	$ 10,459	$ 13,274
Operating Segments
Disaggregation Of Revenue [Line Items]
Total revenue	10,459	13,274
Operating Segments | Oil and Gas Markets
Disaggregation Of Revenue [Line Items]
Total revenue	3,758	6,840
Operating Segments | Oil and Gas Markets | Traditional Exploration Product Revenue
Disaggregation Of Revenue [Line Items]
Total revenue	2,726	3,599
Operating Segments | Oil and Gas Markets | Wireless Exploration Product Revenue
Disaggregation Of Revenue [Line Items]
Total revenue	144	2,623
Operating Segments | Oil and Gas Markets | Reservoir Product Revenue
Disaggregation Of Revenue [Line Items]
Total revenue	888	618
Operating Segments | Adjacent Markets
Disaggregation Of Revenue [Line Items]
Total revenue	6,613	6,434
Operating Segments | Adjacent Markets | Industrial Product Revenue
Disaggregation Of Revenue [Line Items]
Total revenue	3,562	3,676
Operating Segments | Adjacent Markets | Imaging Product Revenue
Disaggregation Of Revenue [Line Items]
Total revenue	3,051	$ 2,758
Operating Segments | Emerging Markets
Disaggregation Of Revenue [Line Items]
Total revenue	$ 88