Condensed Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	3 Months Ended			6 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	[1]	Dec. 31, 2018	Dec. 31, 2017	[1]
Total revenue	$ 216.8	$ 187.9		$ 419.1	$ 366.7
Costs and expenses:
Research and development expense	22.4	16.8		43.5	34.6
Change in the fair value of contingent consideration	1.0	13.0		1.4	(60.2)
Selling, general, and administrative expense	135.2	107.4		265.1	214.6
Total costs and expenses	210.7	181.6		411.8	276.4
Operating income	6.1	6.3		7.3	90.3
Other income (expense):
Interest income	0.9	0.4		1.6	0.8
Interest expense	(3.4)	(0.7)		(5.6)	(1.6)
Other	0.0	(0.4)		1.1	(0.7)
Total other expense:	(2.5)	(0.7)		(2.9)	(1.5)
Income before income tax	3.6	5.6		4.4	88.8
Income tax provision	1.0	(25.3)		2.6	(20.8)
Net income	2.6	30.9		1.8	109.6
Net loss attributable to non-controlling interest				(0.1)	(0.1)
Net income attributable to Myriad Genetics, Inc. stockholders	$ 2.6	$ 30.9		$ 1.9	$ 109.7
Earnings per share:
Basic	$ 0.04	$ 0.45		$ 0.03	$ 1.59
Diluted	$ 0.03	$ 0.43		$ 0.02	$ 1.54
Weighted average shares outstanding:
Basic	74.2	69.3		73.6	68.9
Diluted	76.5	71.9		76.9	71.2
Molecular Diagnostic Testing [Member]
Total revenue	$ 203.0	$ 173.1		$ 392.0	$ 340.5
Costs and expenses:
Total costs and expenses	44.0	37.7		86.3	73.9
Pharmaceutical and Clinical Services [Member]
Total revenue	13.8	14.8		27.1	26.2
Costs and expenses:
Total costs and expenses	$ 8.1	$ 6.7		$ 15.5	$ 13.5

[1] Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.