Revenue Recognition - Deferred Revenues (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Revenue recognized during the period that was included in deferred revenues at the beginning of the period	$ 5,290
Deferred revenue, current portion	51,227	$ 56,016
Deferred revenue, Long-term	23,128	23,808
Total deferred revenues	74,355	$ 79,824
BGI Genomics
Deferred revenue, current portion	4,700
Foundation Medicine ("FMI")
Deferred revenue, current portion	7,000
BGI Genomics and Foundation Medicine ("FMI")
Revenue recognized during the period that was included in deferred revenues at the beginning of the period	$ 1,000