Revenue - Total Revenue by Product and by US versus Rest of World (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Total revenue	$ 167.3	$ 145.2	$ 529.8	$ 402.4
U.S.
Disaggregation of Revenue [Line Items]
Total revenue	144.5	134.0	464.0	373.3
RoW
Disaggregation of Revenue [Line Items]
Total revenue	22.8	11.2	65.8	29.1
Molecular diagnostic testing
Disaggregation of Revenue [Line Items]
Total revenue	167.3	135.7	505.6	369.5
Molecular diagnostic testing \| U.S.
Disaggregation of Revenue [Line Items]
Total revenue	144.5	124.5	439.8	344.3
Molecular diagnostic testing \| RoW
Disaggregation of Revenue [Line Items]
Total revenue	22.8	11.2	65.8	25.2
Molecular diagnostic - Hereditary Cancer
Disaggregation of Revenue [Line Items]
Total revenue	79.4	80.5	241.5	205.6
Molecular diagnostic - Hereditary Cancer \| U.S.
Disaggregation of Revenue [Line Items]
Total revenue	68.2	72.0	207.1	188.2
Molecular diagnostic - Hereditary Cancer \| RoW
Disaggregation of Revenue [Line Items]
Total revenue	11.2	8.5	34.4	17.4
Molecular diagnostic - Tumor Profiling
Disaggregation of Revenue [Line Items]
Total revenue	32.9	17.0	94.4	41.2
Molecular diagnostic - Tumor Profiling \| U.S.
Disaggregation of Revenue [Line Items]
Total revenue	21.4	14.4	63.9	33.7
Molecular diagnostic - Tumor Profiling \| RoW
Disaggregation of Revenue [Line Items]
Total revenue	11.5	2.6	30.5	7.5
Molecular diagnostic - Prenatal
Disaggregation of Revenue [Line Items]
Total revenue	23.6	16.6	76.7	53.5
Molecular diagnostic - Prenatal \| U.S.
Disaggregation of Revenue [Line Items]
Total revenue	23.5	16.5	76.3	53.2
Molecular diagnostic - Prenatal \| RoW
Disaggregation of Revenue [Line Items]
Total revenue	0.1	0.1	0.4	0.3
Molecular Diagnostic - Pharmacogenomics
Disaggregation of Revenue [Line Items]
Total revenue	24.1	11.9	64.3	40.8
Molecular Diagnostic - Pharmacogenomics \| U.S.
Disaggregation of Revenue [Line Items]
Total revenue	24.1	11.9	64.3	40.8
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	7.3	9.1	28.2	26.8
Molecular Diagnostic - Autoimmune \| U.S.
Disaggregation of Revenue [Line Items]
Total revenue	7.3	9.1	28.2	26.8
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	0.0	0.6	0.5	1.6
Molecular diagnostic - Other \| U.S.
Disaggregation of Revenue [Line Items]
Total revenue	0.0	0.6	0.0	1.6
Molecular diagnostic - Other \| RoW
Disaggregation of Revenue [Line Items]
Total revenue	0.0	0.0	0.5	0.0
Pharmaceutical and clinical services
Disaggregation of Revenue [Line Items]
Total revenue	0.0	9.5	24.2	32.9
Pharmaceutical and clinical services \| U.S.
Disaggregation of Revenue [Line Items]
Total revenue	0.0	9.5	24.2	29.0
Pharmaceutical and clinical services \| RoW
Disaggregation of Revenue [Line Items]
Total revenue	$ 0.0	$ 0.0	$ 0.0	$ 3.9