Revenue - Total Revenue by Product and by US versus Rest of World (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Disaggregation of Revenue [Line Items]
Total revenue	$ 189.4	$ 93.2	$ 362.5	$ 257.2
U.S.
Disaggregation of Revenue [Line Items]
Total revenue	164.8	86.2	319.5	239.3
RoW
Disaggregation of Revenue [Line Items]
Total revenue	24.6	7.0	43.0	17.9
Molecular diagnostic testing
Disaggregation of Revenue [Line Items]
Total revenue	178.7	83.3	338.3	233.8
Molecular diagnostic testing \| U.S.
Disaggregation of Revenue [Line Items]
Total revenue	154.1	76.3	295.3	219.8
Molecular diagnostic testing \| RoW
Disaggregation of Revenue [Line Items]
Total revenue	24.6	7.0	43.0	14.0
Molecular diagnostic - Hereditary Cancer
Disaggregation of Revenue [Line Items]
Total revenue	86.0	39.9	162.1	125.1
Molecular diagnostic - Hereditary Cancer \| U.S.
Disaggregation of Revenue [Line Items]
Total revenue	73.8	34.9	138.9	116.2
Molecular diagnostic - Hereditary Cancer \| RoW
Disaggregation of Revenue [Line Items]
Total revenue	12.2	5.0	23.2	8.9
Molecular diagnostic - Tumor Profiling
Disaggregation of Revenue [Line Items]
Total revenue	29.2	10.5	60.2	24.2
Molecular diagnostic - Tumor Profiling \| U.S.
Disaggregation of Revenue [Line Items]
Total revenue	18.1	8.6	42.3	19.3
Molecular diagnostic - Tumor Profiling \| RoW
Disaggregation of Revenue [Line Items]
Total revenue	11.1	1.9	17.9	4.9
Molecular diagnostic - Prenatal
Disaggregation of Revenue [Line Items]
Total revenue	29.4	16.6	53.1	36.9
Molecular diagnostic - Prenatal \| U.S.
Disaggregation of Revenue [Line Items]
Total revenue	29.2	16.5	52.8	36.7
Molecular diagnostic - Prenatal \| RoW
Disaggregation of Revenue [Line Items]
Total revenue	0.2	0.1	0.3	0.2
Molecular Diagnostic - Pharmacogenomics
Disaggregation of Revenue [Line Items]
Total revenue	22.6	8.5	40.2	28.9
Molecular Diagnostic - Pharmacogenomics \| U.S.
Disaggregation of Revenue [Line Items]
Total revenue	22.6	8.5	40.2	28.9
Molecular Diagnostic - Pharmacogenomics \| RoW
Disaggregation of Revenue [Line Items]
Total revenue	0.0	0.0	0.0	0.0
Molecular Diagnostic - Autoimmune
Disaggregation of Revenue [Line Items]
Total revenue	10.2	7.3	20.9	17.7
Molecular Diagnostic - Autoimmune \| U.S.
Disaggregation of Revenue [Line Items]
Total revenue	10.2	7.3	20.9	17.7
Molecular Diagnostic - Autoimmune \| RoW
Disaggregation of Revenue [Line Items]
Total revenue	0.0	0.0	0.0	0.0
Molecular diagnostic - Other
Disaggregation of Revenue [Line Items]
Total revenue	1.3	0.5	1.8	1.0
Molecular diagnostic - Other \| U.S.
Disaggregation of Revenue [Line Items]
Total revenue	0.2	0.5	0.2	1.0
Molecular diagnostic - Other \| RoW
Disaggregation of Revenue [Line Items]
Total revenue	1.1	0.0	1.6	0.0
Pharmaceutical and clinical services
Disaggregation of Revenue [Line Items]
Total revenue	10.7	9.9	24.2	23.4
Pharmaceutical and clinical services \| U.S.
Disaggregation of Revenue [Line Items]
Total revenue	10.7	9.9	24.2	19.5
Pharmaceutical and clinical services \| RoW
Disaggregation of Revenue [Line Items]
Total revenue	$ 0.0	$ 0.0	$ 0.0	$ 3.9