Summary of Significant Accounting Policies - Schedule of Net Revenue by OCS Product and Country (Detail) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 28, 2019	Sep. 28, 2019	Jun. 29, 2019	Mar. 30, 2019	Dec. 31, 2020		Dec. 31, 2020	Dec. 28, 2019
Net revenue		$ 7,627	$ 7,091	$ 3,391	$ 7,530	$ 6,057	$ 7,205	$ 5,666	$ 4,676	$ 25,639	[1]	$ 25,639	$ 23,604	[1]
United States
Net revenue	[1]									19,239			16,253
Non US
Net revenue										6,400			7,351
OCS Lung net revenue
Net revenue										6,194			8,664
OCS Heart net revenue
Net revenue										14,196			11,442
OCS Liver net revenue
Net revenue										$ 5,249			$ 3,498

[1] Net revenue by country is categorized based on the location of the end customer.