Transition Period Comparative Data (Unaudited) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	6 Months Ended	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2021	Dec. 31, 2020	Jun. 30, 2020	Jun. 30, 2019
Transition Period Financial Information [Line Items]
Total revenue	$ 299.8	$ 381.4	$ 690.6	$ 557.1	$ 638.6	$ 851.1
Costs and expenses:
Research and development expense	35.8	40.1	81.9	73.3	77.2	85.9
Selling, general, and administrative expense	260.4	270.4	537.8	496.9	507.3	556.6
Goodwill and long-lived asset impairment charges	0.0	1.3	1.8	98.4	99.7	0.0
Total costs and expenses	387.6	411.1	881.1	846.8	870.3	843.5
Operating income (loss)	(87.8)	(29.7)	(190.5)	(289.7)	(231.7)	7.6
Other income (expense):
Interest income	0.7	1.7	0.7	2.0	3.0	3.2
Interest expense	(5.8)	(5.4)	(6.6)	(11.2)	(10.8)	(12.0)
Other	(1.2)	(0.3)	139.3	15.3	16.2	1.2
Total other income (expense)	(6.3)	(4.0)	133.4	6.1	8.4	(7.6)
Income (loss) before income tax	(94.1)	(33.7)	(57.1)	(283.6)	(223.3)	0.0
Income tax benefit	(41.0)	(4.8)	(29.9)	(59.9)	(23.7)	(4.4)
Net income (loss)	(53.1)	(28.9)	(27.2)	(223.7)	(199.6)	4.4
Net loss attributable to non-controlling interest	0.0	0.0	0.0	(0.1)	(0.1)	(0.2)
Net income (loss) attributable to Myriad Genetics, Inc. stockholders	$ (53.1)	$ (28.9)	$ (27.2)	$ (223.6)	$ (199.5)	$ 4.6
Earnings (loss) per share:
Basic (in dollars per share)	$ (0.71)	$ (0.39)	$ (0.35)	$ (2.99)	$ (2.69)	$ 0.06
Diluted (in dollars per share)	$ (0.71)	$ (0.39)	$ (0.35)	$ (2.99)	$ (2.69)	$ 0.06
Weighted average shares outstanding:
Basic (weighted average shares)	75.0	74.1	78.0	74.8	74.3	73.5
Diluted (weighted average shares)	75.0	74.1	78.0	74.8	74.3	76.0
Molecular diagnostic revenues
Transition Period Financial Information [Line Items]
Total revenue	$ 279.6	$ 353.1	$ 666.4	$ 513.5	$ 586.9	$ 789.4
Costs and expenses:
Costs and expenses	82.6	82.2	185.7	157.9	157.5	168.2
Pharmaceutical and clinical services
Transition Period Financial Information [Line Items]
Total revenue	20.2	28.3	24.2	43.6	51.7	61.7
Costs and expenses:
Costs and expenses	$ 8.8	$ 17.1	$ 11.9	$ 20.3	$ 28.6	$ 32.8

Transition Period Financial Information

No definition available.

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- Definition

The aggregate costs related to goods produced and sold and services rendered by an entity during the reporting period. This excludes costs incurred during the reporting period related to financial services rendered and other revenue generating activities.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 924
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 11.L)
-URI http://asc.fasb.org/extlink&oid=6472922&loc=d3e499488-122856

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.2(a),(d))
-URI http://asc.fasb.org/extlink&oid=123367319&loc=SL114868664-224227