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				6 Months Ended	9 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2020	Jun. 30, 2020	Jun. 30, 2019
Disaggregation Of Revenue [Line Items]
Total revenue	$ 6,975	$ 9,517	$ 9,083	$ 12,153	$ 18,600	$ 25,575	$ 34,457
Operating Segments
Disaggregation Of Revenue [Line Items]
Total revenue	6,975			12,153		25,575	34,457
Operating Segments | Oil and Gas Markets
Disaggregation Of Revenue [Line Items]
Total revenue	1,802			3,931		6,789	12,254
Operating Segments | Oil and Gas Markets | Traditional Exploration Product Revenue
Disaggregation Of Revenue [Line Items]
Total revenue	1,162			2,129		4,749	8,116
Operating Segments | Oil and Gas Markets | Wireless Exploration Product Revenue
Disaggregation Of Revenue [Line Items]
Total revenue	453			1,381		1,336	1,835
Operating Segments | Oil and Gas Markets | Reservoir Product Revenue
Disaggregation Of Revenue [Line Items]
Total revenue	187			421		704	2,303
Operating Segments | Adjacent Markets
Disaggregation Of Revenue [Line Items]
Total revenue	5,085			8,211		18,229	22,058
Operating Segments | Adjacent Markets | Industrial Product Revenue
Disaggregation Of Revenue [Line Items]
Total revenue	3,403			5,364		11,185	13,046
Operating Segments | Adjacent Markets | Imaging Product Revenue
Disaggregation Of Revenue [Line Items]
Total revenue	1,682			2,847		7,044	9,012
Operating Segments | Emerging Markets
Disaggregation Of Revenue [Line Items]
Total revenue	$ 88			$ 11		$ 557	$ 145