Leases - Additional Information (Details) $ in Thousands		1 Months Ended			6 Months Ended	12 Months Ended
	Jan. 21, 2020 renewal_term	Nov. 30, 2016 ft²	Oct. 31, 2014	May 31, 2013 ft² renewal_term	Dec. 31, 2019 USD ($)	Jun. 30, 2020 USD ($)	Aug. 03, 2020 USD ($)	Jul. 01, 2019 USD ($)	Jun. 30, 2019 USD ($)	Jun. 01, 2018 ft²	Feb. 28, 2015 ft²
Leases [Line Items]
Accumulated deficit						$ (199,779)			$ (191,698)
Cash payments for operating leases						387
Cash payments for financing leases						$ 4
1st Detect
Leases [Line Items]
Lease, expiration date			Apr. 30, 2020
Leased premises, right of first refusal exercised | ft²											9,138
Austin, Texas
Leases [Line Items]
Leased premises | ft²		5,219
Lease, expiration date		Dec. 31, 2023
Austin, Texas | Subsequent Event
Leases [Line Items]
Decrease in operating lease ROU asset							$ 539
Decrease in operating lease liability							$ 506
Webster, Texas
Leases [Line Items]
Lease, expiration date	Apr. 30, 2021
Lessee, Operating Lease, Existence of Option to Extend [true false]	true
Number of renewal terms | renewal_term	1
Renewal term	1 year
Original lease area of land removed | ft²										8,118
Leased premises remaining area | ft²										17,560
Adjustment for operating lease right of use asset					$ 414
Adjustment for operating lease liability					$ 414
Webster, Texas | 1st Detect | Research and Development and Production Facility
Leases [Line Items]
Leased premises | ft²				16,540
Lease, expiration date				Jun. 30, 2018
Lessee, Operating Lease, Existence of Option to Extend [true false]				true
Number of renewal terms | renewal_term				2
Renewal term				5 years
Lease term				62 months
Adjustment to Opening Retained Earnings Related to Adoption ASC Topic 842 | ASU 2016-02
Leases [Line Items]
Accumulated deficit								$ 230