Share-Based Compensation - Schedule of Share-Based Compensation Recognized in Consolidated Statements of Operations (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense	$ 7.5	$ 9.5	$ 23.3	$ 24.7
Molecular Diagnostic Testing Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense	0.3	0.3	0.9	0.6
Pharmaceutical and Clinical Services Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense	0.1	0.1	0.2	0.2
Research and Development Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense	1.2	1.7	3.8	3.9
Selling, General, and Administrative Expenses [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense	$ 5.9	$ 7.4	$ 18.4	$ 20.0