Acquisitions - Acquisition of a Business (Details) - USD ($) $ in Thousands		3 Months Ended	6 Months Ended
	Dec. 14, 2020	Jun. 30, 2021	Jun. 30, 2021	Dec. 31, 2020
Business Acquisition [Line Items]
Measurement period adjustment			$ 63
Goodwill		$ 112,901	$ 112,901	$ 112,838
Shooter Detection Systems
Business Acquisition [Line Items]
Percentage of business acquired	100.00%
Consideration	$ 26,600
Purchase price adjustment	(100)	100
Measurement period adjustment		$ 100
Goodwill	7,239
Customer Relationships | Shooter Detection Systems
Business Acquisition [Line Items]
Intangible assets acquired	$ 2,362
Weighted-average estimated useful life of intangible assets acquired	6 years
Developed Technology | Shooter Detection Systems
Business Acquisition [Line Items]
Intangible assets acquired	$ 13,522
Weighted-average estimated useful life of intangible assets acquired	7 years
Trade Name | Shooter Detection Systems
Business Acquisition [Line Items]
Intangible assets acquired	$ 512
Weighted-average estimated useful life of intangible assets acquired	5 years