Employee Deferred Savings Plan - Additional Information (Detail)	6 Months Ended
Dec. 31, 2018
Compensation And Retirement Disclosure [Abstract]
Percent of employee contribution to deferred savings plan	50.00%
Employer's contribution not to exceed percentage of the employees compensation	4.00%

Employers contribution not to exceed percentage of the employees compensation.

No definition available.

Name:	mygn_EmployersContributionNotToExceedPercentageOfEmployeesCompensation
Namespace Prefix:	mygn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration