Revenue - Summary of Revenue Disaggregated by Types and Geography (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation Of Revenue [Line Items]
Product, service and distribution rights revenue	$ 20,862	$ 17,666	$ 71,313	$ 60,299
Product
Disaggregation Of Revenue [Line Items]
Product, service and distribution rights revenue	18,696	16,492	65,475	57,237
Service
Disaggregation Of Revenue [Line Items]
Product, service and distribution rights revenue	2,048	1,056	5,482	2,706
Distribution Rights
Disaggregation Of Revenue [Line Items]
Product, service and distribution rights revenue	118	118	356	356
U.S.
Disaggregation Of Revenue [Line Items]
Product, service and distribution rights revenue	7,247	6,753	31,488	27,239
U.S. | Product
Disaggregation Of Revenue [Line Items]
Product, service and distribution rights revenue	6,107	6,187	28,394	25,775
U.S. | Service
Disaggregation Of Revenue [Line Items]
Product, service and distribution rights revenue	1,140	566	3,094	1,464
Outside of U.S. ("OUS")
Disaggregation Of Revenue [Line Items]
Product, service and distribution rights revenue	13,615	10,913	39,825	33,060
Outside of U.S. ("OUS") | Product
Disaggregation Of Revenue [Line Items]
Product, service and distribution rights revenue	12,589	10,305	37,081	31,462
Outside of U.S. ("OUS") | Service
Disaggregation Of Revenue [Line Items]
Product, service and distribution rights revenue	908	490	2,388	1,242
Outside of U.S. ("OUS") | Distribution Rights
Disaggregation Of Revenue [Line Items]
Product, service and distribution rights revenue	$ 118	$ 118	$ 356	$ 356