Myriad Genetics (MYGN) 10-Q 7 Nov 18 2019 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Sep. 30, 2018	Nov. 02, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,019
Document Fiscal Period Focus	Q1
Trading Symbol	MYGN
Entity Registrant Name	MYRIAD GENETICS INC
Entity Central Index Key	899,923
Current Fiscal Year End Date	--06-30
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		74,762,001

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Sep. 30, 2018	Jun. 30, 2018
Current assets:
Cash and cash equivalents	$ 93.3	$ 110.9
Marketable investment securities	74.2	69.7
Prepaid expenses	11.5	9.4
Inventory	35.9	34.3
Trade accounts receivable	119.1	99.5
Prepaid taxes	3.6
Other receivables	4.3	3.8
Total current assets	341.9	327.6
Property, plant and equipment, net	60	43.2
Long-term marketable investment securities	24.2	30.7
Intangibles, net	734.2	455.2
Goodwill	413.3	318.6
Total assets	1,573.6	1,175.3
Current liabilities:
Accounts payable	23.8	26
Accrued liabilities	76.4	68.3
Short-term contingent consideration	5.3	5.3
Deferred revenue	2.5	2.6
Total current liabilities	108	102.2
Unrecognized tax benefits	24.6	24.9
Other long-term liabilities	6.3	6.3
Contingent consideration	9.6	9.2
Long-term debt	258	9.3
Long-term deferred taxes	64.9	57.3
Total liabilities	471.4	209.2
Commitments and contingencies
Stockholders’ equity:
Common stock, 74.7 and 70.6 shares outstanding at September 30, 2018 and June 30, 2018 respectively	0.7	0.7
Additional paid-in capital	1,052.4	915.4
Accumulated other comprehensive loss	(4.3)	(4.1)
Retained earnings	53.4	54.1
Total Myriad Genetics, Inc. stockholders’ equity	1,102.2	966.1
Total stockholders' equity	1,102.2	966.1
Total liabilities and stockholders’ equity	$ 1,573.6	$ 1,175.3

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - shares shares in Millions	Sep. 30, 2018	Jun. 30, 2018	Jun. 30, 2017
Statement Of Financial Position [Abstract]
Common stock, shares outstanding	74.7	70.6	68.4

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Total revenue	$ 202.3	$ 178.8
Costs and expenses:
Research and development expense	21.1	17.8
Change in the fair value of contingent consideration	0.4	(73.2)
Selling, general, and administrative expense	129.9	107.2
Total costs and expenses	201.1	94.8
Operating income	1.2	84
Other income (expense):
Interest income	0.7	0.4
Interest expense	(2.2)	(0.9)
Other	1.1	(0.3)
Total other expense:	(0.4)	(0.8)
Income before income tax	0.8	83.2
Income tax provision	1.6	4.5
Net income (loss)	(0.8)	78.7
Net loss attributable to non-controlling interest	(0.1)	(0.1)
Net income (loss) attributable to Myriad Genetics, Inc. stockholders	$ (0.7)	$ 78.8
Earnings (loss) per share:
Basic	$ (0.01)	$ 1.15
Diluted	$ (0.01)	$ 1.12
Weighted average shares outstanding:
Basic	73	68.6
Diluted	73	70.4
Molecular Diagnostic Testing [Member]
Total revenue	$ 189	$ 167.4
Costs and expenses:
Total costs and expenses	42.3	36.2
Pharmaceutical and Clinical Services [Member]
Total revenue	13.3	11.4
Costs and expenses:
Total costs and expenses	$ 7.4	$ 6.8

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss) attributable to Myriad Genetics, Inc. stockholders	$ (0.7)	$ 78.8
Unrealized gain (loss) on available-for-sale securities, net of tax	(0.2)	0
Change in foreign currency translation adjustment, net of tax	0.4	3.3
Comprehensive income (loss)	(0.5)	82.1
Comprehensive income attributable to non-controlling interest	0	0
Comprehensive income (loss) attributable to Myriad Genetics, Inc. shareholders	$ (0.5)	$ 82.1

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders' Equity - 3 months ended Sep. 30, 2018 - USD ($) $ in Millions	Total	Common Stock [Member]	Additional paid-in capital [Member]	Accumulated other comprehensive loss [Member]	Retained earnings (accumulated deficit) [Member]
Beginning Balance at Jun. 30, 2018	$ 966.1	$ 0.7	$ 915.4	$ (4.1)	$ 54.1
Issuance of common stock under share-based compensation plans	1.9		1.9
Issuance of common stock for acquisition	127.4		127.4
Share-based payment expense	7.7		7.7
Net income (loss)	(0.7)				(0.7)
Other comprehensive income, net of tax	(0.2)			(0.2)
Ending Balance at Sep. 30, 2018	$ 1,102.2	$ 0.7	$ 1,052.4	$ (4.3)	$ 53.4

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income (loss) attributable to Myriad Genetics, Inc. stockholders	$ (0.7)	$ 78.8
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	18.3	13.2
Non-cash interest expense	(1.3)	0.1
Loss (gain) on disposition of assets	(1)	(0.1)
Share-based compensation expense	7.7	6.4
Deferred income taxes	2.7	4.7
Unrecognized tax benefits	(2.6)	6.7
Change in fair value of contingent consideration	(0.4)	(73.2)
Changes in assets and liabilities:
Prepaid expenses	1.8	3.2
Trade accounts receivable	(3.3)	(6.2)
Other receivables	(0.3)	0.3
Inventory	3.5	3.3
Prepaid taxes	(3.6)	(8.9)
Accounts payable	(8.4)	0.4
Accrued liabilities	(4.4)	(5.8)
Deferred revenue	(0.2)	0.6
Net cash provided by operating activities	7.8	23.5
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(1.3)	(1.6)
Acquisitions, net of cash acquired	(279.6)
Purchases of marketable investment securities	(14.4)	(31.5)
Proceeds from maturities and sales of marketable investment securities	16.3	17.9
Net cash used in investing activities	(279)	(15.2)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net proceeds from common stock issued under share-based compensation plans	2.1	1.7
Net proceeds from revolving credit facility	290
Repayment of revolving credit facility	(40)	(25)
Net cash provided by (used in) financing activities	252.1	(23.3)
Effect of foreign exchange rates on cash and cash equivalents	1.5	0.5
Net decrease in cash and cash equivalents	(17.6)	(14.5)
Cash and cash equivalents at beginning of the period	110.9	102.4
Cash and cash equivalents at end of the period	$ 93.3	$ 87.9

Basis of Presentation

Basis of Presentation	3 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation	(1) BASIS OF PRESENTATION The accompanying condensed consolidated financial statements have been prepared by Myriad Genetics, Inc. (the “Company” or “Myriad”) in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and pursuant to the applicable rules and regulations of the Securities and Exchange Commission (“SEC”). The condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation. In the opinion of management, the accompanying financial statements contain all adjustments (consisting of normal and recurring accruals) necessary to present fairly all financial statements in accordance with GAAP. The condensed consolidated financial statements herein should be read in conjunction with the Company’s audited consolidated financial statements and notes thereto for the fiscal year ended June 30, 2018, included in the Company’s Annual Report on Form 10-K for the fiscal year ended June 30, 2018. Operating results for the three months ended September 30, 2018 may not necessarily be indicative of results to be expected for any other interim period or for the full year. The consolidated financial statements include the accounts of the Company’s majority-owned subsidiary, Assurex Canada, Ltd. which is 85% owned by Assurex Health, Inc. (“Assurex”), a wholly owned subsidiary of the Company, and 15% owned by the Centre for Addiction and Mental Health. Assurex Canada, Ltd. is a consolidated subsidiary of Assurex Health, Inc. The value of the non-controlling interest represents the portion of Assurex Canada, Ltd.’s profit or loss and net assets that is not held by Assurex Health, Inc. The Company attributes comprehensive income or loss of the subsidiary between the Company and the non-controlling interest based on the respective ownership interest. The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements, as well as the reported amounts of revenue and expenses during the reporting period. Actual results could differ from those estimates. New Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (FASB) issued the converged standard on revenue recognition with the objective of providing a single, comprehensive model for all contracts with customers to improve comparability in the financial statements of companies reporting using International Financial Reporting Standards and U.S. GAAP. The standard contains principles that an entity must apply to determine the measurement of revenue and timing of when it is recognized. The underlying principle is that an entity must recognize revenue to depict the transfer of goods or services to customers at an amount that the entity expects to be entitled to in exchange for those goods or services. An entity can apply the revenue standard retrospectively to each prior reporting period presented (full retrospective method) or retrospectively with the cumulative effect of initially applying the standard recognized at the date of initial application in retained earnings (modified retrospective method). The standard was effective for the Company beginning July 1, 2018. The Company elected to adopt the standard using the full retrospective approach, which resulted in a recasting of revenue and the related financial statement items for FY2017 and FY2018. During transition to the new standard, the Company also elected several practical expedients, as provided by the standard. Contracts that began and ended within the same annual reporting period were not restated. Contracts that were completed by June 30, 2018 that had variable consideration were estimated using the transaction price at the date the contract was completed. The amount of the transaction price allocated to the remaining performance obligations will not be disclosed for prior reporting periods. Contracts that were modified prior to the earliest reporting period will be reflected in the earliest reporting period with an aggregate adjustment for prior modifications. As a result of the new standard, the Company has changed its accounting policies for revenue recognition. The primary impact of the new standard was classifying bad debt expense of $8.0 for the three months ended September 30, 2017, as a reduction in revenue rather than as a selling, general and administrative expense. The Company also increased its June 30, 2018 accounts receivable and retained earnings balances by $1.2 as a result of adopting the new standard. Reclassifications Adoption of new revenue recognition standard impacted the Company’s previously reported results as follows: Three months ended September 30, 2017 As Previously Reported ASC606 Adjustments As Restated Consolidated Statements of Operations: Total Revenue $ 187.9 $ (9.1 ) $ 178.8 Selling, general and administrative expense 115.2 (8.0 ) 107.2 Income tax provision 4.8 (0.3 ) 4.5 Net Income attributable to Myriad Genetics, Inc. stockholders 79.6 (0.8 ) 78.8 Earnings per share: Basic $ 1.16 $ (0.01 ) $ 1.15 Diluted $ 1.13 $ (0.01 ) $ 1.12 Consolidated Statements of Cash Flows: Net Income attributable to Myriad Genetics, Inc. stockholders 79.6 (0.8 ) $ 78.8 Trade Accounts Receivable (16.5 ) 10.3 (6.2 ) June 30, 2018 As Previously Reported ASC606 Adjustments As Restated Consolidated Balance Sheet: Trade accounts receivable $ 98.3 $ 1.2 $ 99.5 Retained Earnings 52.9 1.2 54.1 In February 2016, the FASB issued Accounting Standards Update (“ASU”) 2016-02, Leases. ASU 2016-02 amends the existing accounting standards for lease accounting, including requiring lessees to recognize most leases on their balance sheets and making targeted changes to lessor accounting. ASU 2016-02 will be effective beginning in the first quarter of fiscal 2020. Early adoption of ASU 2016-02 is permitted. ASU 2016-02 requires a modified retrospective transition approach for all leases existing at, or entered into after, the date of initial application, with an option to use certain transition relief. The Company’s management is currently evaluating the impact of adopting ASU 2016-02 on the Company’s consolidated financial statements. In accordance with the Securities Act Release No. 33-10532 which now requires presenting changes in stockholders equity quarterly we have included our condensed consolidated statements of equity.

Revenue

Revenue	3 Months Ended
	Sep. 30, 2018
Revenue From Contract With Customer [Abstract]
Revenue	(2) REVENUE The following table presents detail regarding the composition of our total revenue by product and U.S versus rest of world, “RoW”: Three months ended September 30, 2018 2017 (In millions) U.S. RoW Total U.S. RoW Total Molecular diagnostic revenues: Hereditary Cancer Testing $ 113.5 $ 2.8 $ 116.3 $ 114.6 $ 2.4 $ 117.0 GeneSight 29.3 29.3 28.8 28.8 Prenatal 18.1 — 18.1 — — — VectraDA 13.0 — 13.0 14.0 — 14.0 Prolaris 6.2 — 6.2 3.9 — 3.9 EndoPredict 0.3 2.1 2.4 0.0 1.8 1.8 Other 3.6 0.1 3.7 1.8 0.1 1.9 Total molecular diagnostic revenue 184.0 5.0 189.0 163.1 4.3 167.4 Pharmaceutical and clinical service revenue 7.6 5.7 13.3 6.3 5.1 11.4 Total revenue $ 191.6 $ 10.7 $ 202.3 $ 169.4 $ 9.4 $ 178.8 The Company performs its obligation under a contract with a customer by processing diagnostic tests and communicating the test results to customers, in exchange for consideration from the customer. The Company has the right to bill its customers upon the completion of performance obligations and thus does not record contract assets. Occasionally customers make payments prior to the Company's performance of its contractual obligations. When this occurs the Company records a contract liability as deferred revenue. A reconciliation of the beginning and ending balances of deferred revenue is shown in the table below: Three months ended September 30, 2018 2017 Deferred revenue - beginning balance $ 2.6 $ 2.6 Revenue recognized (1.7 ) (5.9 ) Prepayments 1.6 6.2 Deferred revenue - Ending Balance $ 2.5 $ 2.9 Myriad Companies generate revenue by performing molecular diagnostic testing and pharmaceutical & clinical services. Revenue from the sale of molecular diagnostic tests and pharmaceutical and clinical services is recorded at the invoiced amount net of any discounts or contractual allowances. The Company has determined that the communication of test results or the completion of clinical and pharmaceutical services indicates transfer of control for revenue recognition purposes. In accordance with ASU 2014-09, the Company has elected not to disclose the aggregate amount of the transaction price allocated to remaining performance obligations for its contracts that are one year or less, as the revenue is expected to be recognized within the next year. Furthermore, the Company has elected not to disclose the aggregate amount of the transaction price allocated to remaining performance obligations for its agreements wherein the Company’s right to payment is in an amount that directly corresponds with the value of Company’s performance to date. However, periodically the Company enters into arrangements with customers to provide diagnostic testing and/or pharmaceutical and clinical services that may have terms longer than one year and include multiple performance obligations. As of September 30, 2018, the aggregate amount of the transaction price of such contracts that is allocated to the remaining performance obligations is $7.3, $4.3 of which the Company expects to recognize in fiscal 2019. Significant judgments are required in determining the transaction price and satisfying performance obligations under the new revenue standard. The Company provides discounts such as early payment, self-pay and volume discounts to its customers. In determining the transaction price, Myriad includes an estimate of the expected amount of consideration as revenue. The Company applies this method consistently for similar contracts when estimating the effect of any uncertainty on an amount of variable consideration to which it will be entitled. An estimate of transaction price does not include any estimated amount of variable consideration that are constrained. The Company applies the expected value method for sales where the Company has a large number of contracts with similar characteristics. In addition, the Company considers all the information (historical, current, and forecast) that is reasonably available to identify possible consideration amounts. In determining the expected value under the new standard, the Company considers the probability of the variable consideration for each possible scenario. The Company also has significant experience with historical discount patterns and uses this experience to estimate transaction prices. In accordance with ASU 2016-12, the Company has elected to exclude from the measurement of transaction price, all taxes assessed by a governmental authority that are both imposed on and concurrent with a specific revenue-producing transaction and collected by the Company from a customer for e.g. sales tax, value added tax etc. The Company has elected to apply the practical expedient related to costs to obtain or fulfill a contract since the amortization period for such costs will be one year or less. Accordingly no costs incurred to obtain or fulfill a contract have been capitalized. The Company has also elected to apply the practical expedient for not adjusting revenue recognized for the effects of the time value of money. This practical expedient has been elected because the Company collects very little cash from customers under payment terms and vast majority of payments terms have a payback period of less than one year.

Acquisitions

Acquisitions	3 Months Ended
	Sep. 30, 2018
Business Combinations [Abstract]
Acquisitions	(3) ACQUISITIONS Acquisition of Counsyl, Inc. On July 31, 2018, the Company completed the acquisition of Counsyl, Inc. (“Counsyl”), a leading provider of genetic testing and DNA analysis services, pursuant to the Agreement and Plan of Merger (the “Merger Agreement”), dated May 25, 2018. Pursuant to the terms of the Merger Agreement, Myriad Merger Sub, Inc., a newly-created wholly-owned subsidiary of the Company, was merged with and into Counsyl, with Counsyl continuing as the surviving corporation and a wholly-owned subsidiary of Myriad. The Company believes the acquisition allows for greater entry into the high-growth reproductive testing market, with the ability to become a leader in women’s health genetic testing. The Company acquired Counsyl for total consideration of $407.0, consisting of $279.6 in cash, financed in part by the Amendment to the Facility (see Note 8) and 2,994,251 shares of common stock issued, valued at $127.4. The shares were issued and valued as of July 31, 2018 at a per share market closing price of $42.53. Of the cash consideration, $5.0 was deposited into an escrow account to fund any post-closing adjustments payable to Myriad based upon differences between the estimated working capital and the actual working capital of Counsyl at closing. Consideration transferred was allocated to the tangible and intangible assets acquired and liabilities assumed based on their fair values as of the acquisition date. Management estimated the fair value of tangible and intangible assets and liabilities in accordance with the applicable accounting guidance for business combinations and utilized the services of third-party valuation consultants. The initial allocation of the consideration transferred is based on a preliminary valuation and is subject to potential adjustments. Balances subject to adjustment primarily include the valuations of acquired assets (tangible and intangible), liabilities assumed, as well as tax-related matters. During the measurement period, the Company may record adjustments to the provisional amounts recognized. The Company expects the allocation of the consideration transferred to be final within the measurement period (up to one year from the acquisition date). Estimated Fair Value Current assets $ 42.5 Intangible assets 292.9 Equipment 18.9 Other assets 0.1 Goodwill 94.9 Current liabilities (19.6 ) Long term liabilities (0.1 ) Deferred tax liability (7.3 ) Total fair value purchase price $ 422.3 Less: Cash acquired (15.3 ) Total consideration transferred $ 407.0 Identifiable Intangible Assets The Company acquired intangible assets that consisted of developed screening processes which had an estimated fair value of $292.0 and internally developed software with an estimated fair value of $0.9. The fair values of these developed screening processes and related useful lives were determined using a probability-weighted income approach that discounts expected future cash flows to present value. The estimated net cash flows were discounted using a discount rate of 12.5% which is based on the estimated internal rate of return for the acquisition and represents the rate that market participants might use to value the intangible assets. The fair value of the internally developed software was determined based on a replacement cost approach. The Company will amortize the intangible assets on a straight-line basis over their estimated useful lives of 12 years for the developed screening processes and 5 years for the internally developed software. Goodwill The $94.9 of goodwill represents the excess of consideration transferred over the fair value of assets acquired and liabilities assumed and is attributable to the benefits expected from combining the Company’s expertise with Counsyl’s technology, customer insights, and ability to effectively integrate genetic screening into clinical practice with OBGYNs. This goodwill is not deductible for income tax purposes. Pro Forma Information The unaudited pro-forma results presented below include the effects of the Counsyl acquisition as if it had been consummated as of July 1, 2017, with adjustments to give effect to pro forma events that are directly attributable to the acquisition, which includes adjustments related to the amortization of acquired intangible assets, interest income and expense, and depreciation. The unaudited pro forma results do not reflect any operating efficiency or potential cost savings that may result from the consolidation of Counsyl. Accordingly, these unaudited pro forma results are presented for informational purposes only and are not necessarily indicative of what the actual results of operation of the combined company would have been if the acquisition had occurred at the beginning of the period presented nor are they indicative of future results of operations and are not necessarily indicative of results that might have been achieved had the acquisition been consummated as of July 1, 2017. Three months ended September 30, 2018 2017 Revenue $ 212.5 $ 209.5 Income from operations 11.5 69.6 Net income 8.6 61.3 Net income per share, basic $ 0.11 $ 0.86 Net income per share, diluted $ 0.11 $ 0.84 To complete the purchase transaction, we incurred approximately $6.8 of acquisition costs, which are recorded as selling, general and administrative expenses in the period incurred. For the three months ended September 30, 2018, Counsyl contributed revenue of approximately $19.4. For the three months ended September 30, 2018, operating expenses related to Counsyl were approximately $33.0.

Marketable Investment Securitie

Marketable Investment Securities	3 Months Ended
	Sep. 30, 2018
Investments Debt And Equity Securities [Abstract]
Marketable Investment Securities	(4) MARKETABLE INVESTMENT SECURITIES The Company has classified its marketable investment securities as available-for-sale securities. These securities are carried at estimated fair value with unrealized holding gains and losses, net of the related tax effect, included in accumulated other comprehensive loss in stockholders’ equity until realized. Gains and losses on investment security transactions are reported on the specific-identification method. Dividend and interest income are recognized when earned. The Conpany’s cash equivalents consist of short-term, highly liquid investments that are readily convertible to known amounts of cash. The amortized cost, gross unrealized holding gains, gross unrealized holding losses, and fair value for available-for-sale securities by major security type and class of security at September 30, 2018 and June 30, 2018 were as follows: Gross Gross unrealized unrealized Amortized holding holding Estimated cost gains losses fair value At September 30, 2018: Cash and cash equivalents: Cash $ 75.3 $ — $ — $ 75.3 Cash equivalents 18.0 — — $ 18.0 Total cash and cash equivalents 93.3 — — 93.3 Available-for-sale: Corporate bonds and notes 57.5 — (0.3 ) 57.2 Municipal bonds 23.4 — (0.1 ) 23.3 Federal agency issues 9.6 — — 9.6 US government securities 8.3 — — 8.3 Total $ 192.1 $ — $ (0.4 ) $ 191.7 Gross Gross unrealized unrealized Amortized holding holding Estimated cost gains losses fair value At June 30, 2018: Cash and cash equivalents: Cash $ 95.6 $ — $ — $ 95.6 Cash equivalents 15.3 — — 15.3 Total cash and cash equivalents 110.9 — — 110.9 Available-for-sale: Corporate bonds and notes 50.8 — (0.3 ) 50.5 Municipal bonds 29.3 — (0.1 ) 29.2 Federal agency issues 12.6 — (0.1 ) 12.5 US government securities 8.3 — (0.1 ) 8.2 Total $ 211.9 $ — $ (0.6 ) $ 211.3 Cash, cash equivalents, and maturities of debt securities classified as available-for-sale securities are as follows at September 30, 2018: Amortized Estimated cost fair value Cash $ 75.3 $ 75.3 Cash equivalents 18.0 18.0 Available-for-sale: Due within one year 75.9 75.6 Due after one year through five years 22.9 22.8 Due after five years — — Total $ 192.1 $ 191.7

Property, Plant and Equipment,

Property, Plant and Equipment, Net	3 Months Ended
	Sep. 30, 2018
Property Plant And Equipment [Abstract]
Property, Plant and Equipment, Net	(5) PROPERTY, PLANT AND EQUIPMENT, NET September 30, June 30, 2018 2018 Land $ 2.4 $ 2.4 Buildings and improvements 19.2 19.3 Leasehold improvements 29.9 23.0 Equipment 113.0 112.4 164.5 157.1 Less accumulated depreciation (104.5 ) (113.9 ) Property, plant and equipment, net $ 60.0 $ 43.2 Three months ended September 30, 2018 2017 Depreciation expense $ 4.9 $ 3.9

Goodwill and Intangible Assets

Goodwill and Intangible Assets	3 Months Ended
	Sep. 30, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	(6) GOODWILL AND INTANGIBLE ASSETS Goodwill The Company has recorded goodwill of $413.3 from the acquisitions of Counsyl that was completed on July 31, 2018, Assurex that was completed on August 31, 2016, Sividon Diagnostics GmbH (“Sividon”) that was completed on May 31, 2016, Privatklinik Dr. Robert Schindlbeck GmbH & Co. KG (the “Clinic”) that was completed on February 27, 2015, Crescendo Bioscience, Inc. that was completed on February 28, 2014 and Rules-Based Medicine, Inc. that was completed on May 31, 2011. Of this goodwill, $347.5 relates to the Company’s diagnostic segment and $65.8 relates to the other segment. The following summarizes changes to the goodwill balance for the three months ended September 30, 2018: Carrying amount Beginning balance July 1, 2018 $ 318.6 Acquisitions 94.9 Translation adjustments (0.2 ) Ending balance September 30, 2018 $ 413.3 Intangible Assets Intangible assets primarily consist of amortizable assets of purchased licenses and technologies, customer relationships, and trade names as well as non-amortizable intangible assets of in-process technologies and research and development. The following summarizes the amounts reported as intangible assets: Gross Carrying Accumulated Amount Amortization Net At September 30, 2018: Purchased licenses and technologies $ 819.1 $ (111.4 ) $ 707.7 Customer relationships 4.6 (3.4 ) 1.2 Trademarks 3.0 (1.0 ) 2.0 Total amortized intangible assets 826.7 (115.8 ) 710.9 In-process research and development 23.3 — 23.3 Total unamortized intangible assets 23.3 — 23.3 Total intangible assets $ 850.0 $ (115.8 ) $ 734.2 Gross Carrying Accumulated Amount Amortization Net At June 30, 2018: Purchased licenses and technologies $ 526.4 $ (98.0 ) $ 428.4 Customer relationships 4.6 (3.3 ) 1.3 Trademarks 3.0 (1.0 ) 2.0 Total amortized intangible assets 534.0 (102.3 ) 431.7 In-process research and development 23.5 — 23.5 Total unamortized intangible assets 23.5 — 23.5 Total intangible assets $ 557.5 $ (102.3 ) $ 455.2 The Company recorded amortization expense during the respective periods for these intangible assets as follows: Three months ended September 30, 2018 2017 Amortization of intangible assets $ 13.4 $ 9.3

Accrued Liabilities

Accrued Liabilities	3 Months Ended
	Sep. 30, 2018
Payables And Accruals [Abstract]
Accrued Liabilities	(7) ACCRUED LIABILITIES September 30, June 30, 2018 2018 Employee compensation and benefits $ 47.8 $ 49.5 Accrued taxes payable 9.8 4.3 Other 18.8 14.5 Total accrued liabilities $ 76.4 $ 68.3

Long-Term Debt

Long-Term Debt	3 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Long-Term Debt	(8) LONG-TERM DEBT On December 23, 2016, the Company entered into a senior secured revolving credit facility (the “Facility”) by and among Myriad, as borrower, with the lenders from time to time party thereto. On July 31, 2018, the Company entered into Amendment No. 1 (the “Amended Facility”) which effects an “amend and extend” transaction with respect to the Facility by which the maturity date thereof was extended to July 31, 2023 and the maximum aggregate principal commitment was increased from $300.0 to $350.0. This was accounted for as a modification pursuant to guidance in ASC 470-50. Pursuant to the Amended Facility, Myriad borrowed revolving loans in an aggregate principal amount of $300.0 with $1.8 in upfront fees and $0.3 debt issuance costs recorded as a debt discount to be amortized over the term of the Amended Facility resulting in current net long-term debt of $297.9. There are no scheduled principal payments of the Amended Facility prior to its maturity date. The proceeds of the Amended Facility were used to: (i) refinance in full the obligations under the Facility, (ii) finance the acquisition of Counsyl (See Note 3), (iii) pay fees, commissions, transactions costs and expenses incurred in connection with the foregoing, and (iv) for working capital and other general corporate purposes. The Amended Facility contains customary loan terms, interest rates, representations and warranties, affirmative and negative covenants, in each case, subject to customary limitations, exceptions and exclusions. The Amended Facility also contains certain customary events of default. Covenants in the Amended Facility impose operating and financial restrictions on the Company. These restrictions may prohibit or place limitations on, among other things, the Company’s ability to incur additional indebtedness, create certain types of liens, complete mergers or consolidations, and/or change in control transactions. The Amended Facility may also prohibit or place limitations on the Company’s ability to sell assets, pay dividends or provide other distributions to shareholders. The Company must maintain specified leverage and interest ratios measured as of the end of each quarter as a financial covenant in the Amended Facility. We were in compliance with all financial covenants at September 30, 2018. During the quarter ended September 30, 2018, the Company made $40.0 in principal repayments. The Amended Facility is secured by a first-lien security interest in substantially all of the assets of Myriad and certain of its domestic subsidiaries and each such domestic subsidiary of Myriad has guaranteed the repayment of the Amended Facility. Amounts outstanding under the Amended Facility and Facility were as follows: September 30, June 30, 2018 2018 Long-term debt $ 260.1 $ 10.0 Long-term debt discount (2.1 ) (0.7 ) Net long-term debt $ 258.0 $ 9.3

Other Long Term Liabilities

Other Long Term Liabilities	3 Months Ended
	Sep. 30, 2018
Other Liabilities Disclosure [Abstract]
Other Long Term Liabilities	(9) OTHER LONG TERM LIABILITIES September 30, June 30, 2018 2018 Pension obligation 6.1 6.0 Other 0.2 0.3 Total other long term liabilities $ 6.3 $ 6.3 The Company has two non-contributory defined benefit pension plans for certain Clinic employees. Participation in the plans excludes those employees hired after 2002. As of September 30, 2018 the fair value of the plan assets were approximately $0.1 resulting in a net pension liability of $6.1.

Preferred and Common Stockholde

Preferred and Common Stockholder's Equity	3 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Preferred and Common Stockholder's Equity	(10) PREFERRED AND COMMON STOCKHOLDER’S EQUITY The Company is authorized to issue up to 5.0 shares of preferred stock, par value $0.01 per share. There were no preferred shares outstanding at September 30, 2018. The Company is authorized to issue up to 150.0 shares of common stock, par value $0.01 per share. There were 74.7 shares issued and outstanding at September 30, 2018. Common shares issued and outstanding Three months ended Year ended September 30, June 30, 2018 2018 Common stock issued and outstanding at July 1 70.6 68.4 Common stock issued upon exercise of options and employee stock plans 4.1 2.2 Repurchase and retirement of common stock — — Common stock issued and outstanding at end of period 74.7 70.6 Basic earnings per share is computed based on the weighted-average number of shares of common stock outstanding. Diluted earnings per share is computed based on the weighted-average number of shares of common stock, including the dilutive effect of common stock equivalents, outstanding. In periods when the Company has a net loss, stock awards are excluded from the calculation of diluted net loss per share as their inclusion would have an antidilutive effect. The following is a reconciliation of the denominators of the basic and diluted earnings per share (“EPS”) computations: Three months ended September 30, 2018 2017 Denominator: Weighted-average shares outstanding used to compute basic EPS 73.0 68.6 Effect of dilutive shares — 1.8 Weighted-average shares outstanding and dilutive securities used to compute diluted EPS 73.0 70.4 Certain outstanding options and restricted stock units (“RSUs”) were excluded from the computation of diluted earnings per share because the effect would have been anti-dilutive. These potential dilutive common shares, which may be dilutive to future diluted earnings per share, are as follows: Three months ended September 30, 2018 2017 Anti-dilutive options and RSU's excluded from EPS computation 4.1 1.5 Stock Repurchase Program In June 2016, the Company’s Board of Directors authorized an eighth share repurchase program of $200.0 of the Company’s outstanding common stock. The Company plans to repurchase its common stock from time to time or on an accelerated basis through open market transactions or privately negotiated transactions as determined by the Company’s management. The amount and timing of stock repurchases under the program will depend on business and market conditions, stock price, trading restrictions, acquisition activity and other factors. As of September 30, 2018, the Company has $160.7 remaining on its current share repurchase authorization. The Company uses the par value method of accounting for its stock repurchases. As a result of the stock repurchases, the Company reduced common stock and additional paid-in capital and recorded charges to accumulated deficit. The shares retired, aggregate common stock and additional paid-in capital reductions, and related charges to accumulated deficit for the repurchases for periods ended September 30, 2018 and 2017 were as follows: Three months ended September 30, 2018 2017 Shares purchased and retired — — Common stock and additional paid-in-capital reductions $ — $ — Charges to retained earnings $ — $ —

Income Taxes

Income Taxes	3 Months Ended
	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	(11) INCOME TAXES On December 22, 2017, the Tax Cuts and Jobs Act (the “Tax Act”) was enacted. The Tax Act makes broad and complex changes to the U.S. tax code that will affect our fiscal year ending June 30, 2018, including, but not limited to (1) reducing the U.S. federal corporate tax rate from 35 percent to 21 percent; (2) requiring companies to pay a one-time transition tax on certain unrepatriated earnings of foreign subsidiaries; (3) generally eliminating U.S. federal income taxes on dividends from foreign subsidiaries; (4) requiring a current inclusion in U.S. federal taxable income of certain earnings of controlled foreign corporations; (5) creating the base erosion anti-abuse tax (BEAT), a new minimum tax; (6) creating a new limitation on deductible interest expense; (7) revising the rules that limit the deductibility of compensation to certain highly compensated executives, and (8) changing rules related to uses and limitations of net operating loss carryforwards created in tax years beginning after December 31, 2017. The SEC staff issued SAB 118, which provides guidance on accounting for the tax effects of the Tax Act. SAB 118 provides a measurement period that should not extend beyond one year from the Tax Act enactment date for companies to complete the accounting under ASC 740. In accordance with SAB 118, a company must reflect the income tax effects of those aspects of the Act for which the accounting under ASC 740 is complete. To the extent that a company’s accounting for certain income tax effects of the Tax Act is incomplete but it is able to determine a reasonable estimate, it must record a provisional estimate in the financial statements. If a company cannot determine a provisional estimate to be included in the financial statements, it should continue to apply ASC 740 on the basis of the provisions of the tax laws that were in effect immediately before the enactment of the Tax Act. In connection with our initial analysis of the impact of the Tax Act and consistent with the requirement to record a provisional estimate when applicable, the Company recorded a discrete net income tax benefit during the quarter ended December 31, 2017 of approximately $32.6 ($0.45 earnings per share increase). This provisional estimate primarily consists of a net benefit for the corporate rate reduction due to the revaluing of its net deferred tax liabilities as a result of the reduction in the federal corporate tax rates. The Company’s net deferred tax liabilities represent temporary differences between the book bases of assets which are greater than their tax bases. Upon the reversal of those temporary differences, the future tax impact will be based on the lower federal corporate tax rate enacted by the Tax Act. The Company is continuing to gather information and to analyze aspects of the Tax Act, which could potentially affect the estimated impact on the deferred tax balances. For various reasons that are discussed more fully below, we have not completed our accounting for the income tax effects of certain elements of the Tax Act. To the extent we were not yet able to make reasonable estimates of the impact of certain elements, we have not recorded any adjustments related to those elements and have continued accounting for them in accordance with ASC 740 on the basis of the tax laws in effect before the Tax Act. In addition to the discrete benefit recorded during the quarter ended December 31, 2017 for the provisional estimated impact on the Company’s net deferred tax liabilities, the lower federal corporate tax rate reduced the Company’s estimated annual effective tax rate which was applied to year to date operating results in accordance with the interim accounting guidelines. The Company estimates that the reduction in the federal corporate rate will have an ongoing effect to reduce the Company’s income tax expense from continuing operations. As a result of changes made by the Tax Act, Section 162(m) will limit the deduction of compensation, including performance-based compensation, in excess of $1.0 paid to anyone who, for tax years beginning after January 1, 2018, serves as the Chief Executive Officer or Chief Financial Officer, or who is among the three most highly compensated executive officers for any fiscal year. The only exception to this rule is for compensation that is paid pursuant to a binding written contract in effect on November 2, 2017 that would have otherwise been deductible under the prior Section 162(m) rules. Accordingly, any compensation paid in the future pursuant to new compensation arrangements entered into after November 2, 2017, even if performance-based, will count towards the $1.0 fiscal year deduction limit if paid to a covered executive. The Company estimated that there will not be a material impact during the fiscal year ended June 30, 2018, as the law is effective for tax years beginning after January 1, 2018. The Company has evaluated its binding contracts entered into prior to November 2, 2017, and believes there will be no material impact for adjustments related to deferred equity compensation currently carried as a deferred tax asset on the Company’s balance sheet. The Company is still analyzing certain aspects of the Tax Act and refining calculations, which could potentially affect the impact of this provision. Beginning fiscal year ending June 30, 2018, the company estimates there will be a material impact due to compensation in excess of $1.0. For the quarter ended September 30, 2018, the Company included the impact in the annual effective tax rate applied to the quarter. The Tax Act also implements certain changes on the taxation of the Company’s foreign operations. Our accounting for the following elements of the Tax Act is incomplete, and we were not yet able to make reasonable estimates of the effects. Therefore, no provisional adjustments were recorded. The Deemed Repatriation Transition Tax (Transition Tax) is a tax on previously untaxed accumulated and current earnings and profits (E&P) of certain of our foreign subsidiaries. To determine the amount of the Transition Tax, we must determine, in addition to other factors, the amount of post-1986 E&P of the relevant subsidiaries, as well as the amount of non-U.S. income taxes paid on such earnings. While the Company estimates that there will not be a material impact during the current quarter or current fiscal year due to the Transition Tax, we are not able to make a reasonable estimate of the Transition Tax and have not recorded a provisional amount. We are continuing to gather additional information needed to finalize the amount of post-1986 E&P to more precisely compute the amount of the Transition Tax. Other revisions to the taxation of foreign earnings will not be effective until the Company’s fiscal year ending on June 30, 2019. The Company is in the process of evaluating the additional provisions of the Tax Act that will become effective in their fiscal year ending June 30, 2019. The impact of the Tax Act may differ from these estimates, possibly materially, due to, among other things, changes in interpretations and assumptions the Company has made, guidance that may be issued and actions the Company may take as a result of the Tax Act. The Company will continue to update the provisional estimates as information is obtained, such as state impacts regarding decoupling from the Tax Act provisions, realization of deferred amounts in the fiscal year, and accounting method elections that may be made by the Company. In order to determine the Company’s quarterly provision for income taxes, the Company used an estimated annual effective tax rate that is based on expected annual income and statutory tax rates in the various jurisdictions in which the Company operates. The Tax Act reduces the federal corporate tax rate to 21% in the fiscal year ending June 30, 2018. Section 15 of the Internal Revenue Code Stipulates that our fiscal year ending June 30, 2018, had a blended corporate tax rate of 28%, which is based on the applicable tax rates before and after the Tax Act and the number of days in the year. For the fiscal year ending June 30, 2019, the Company’s federal corporate tax rate is 21%. Certain significant or unusual items are separately recognized in the quarter during which they occur and can be a source of variability in the effective tax rate from quarter to quarter. Income tax expense for the three months ended September 30, 2018 was $1.6, or approximately 200.0% of pre-tax income compared to $4.5, or approximately 5.4% of pre-tax income, for the three months ended September 30, 2017. Income tax expense for the three months ended September 30, 2018 is based on the Company’s estimated annual effective tax rate for the full fiscal year ending June 30, 2019, adjusted by discrete items recognized during the period. For the three months ended September 30, 2018, the Company’s recognized effective tax rate differs from the U.S. federal statutory rate primarily due to the effect of the release of uncertain tax liabilities, recording deferred tax liabilities on foreign branch temporary differences due to a change in tax status, state income taxes, acquisition transaction costs, and differences related to the tax effect of equity compensation expense and the deduction realized when exercised, released or sold. The Company files U.S., foreign and state income tax returns in jurisdictions with various statutes of limitations. The Company is currently under audit by the State of New Jersey for the fiscal years June 30, 2013 through 2017; and Germany for the fiscal years June 30, 2013 through 2015. Annual and interim tax provisions include amounts considered necessary to pay assessments that may result from examination of prior year tax returns; however, the amount ultimately paid upon resolution of issues may differ materially from the amount accrued.

Share-Based Compensation

Share-Based Compensation	3 Months Ended
	Sep. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Share-Based Compensation	(12) SHARE-BASED COMPENSATION On November 30, 2017, the Company’s shareholders approved the adoption of the 2017 Employee, Director and Consultant Equity Incentive Plan (the “2017 Plan”). The 2017 Plan allows the Company, under the direction of the Compensation Committee of the Board of Directors, to make grants of restricted and unrestricted stock awards to employees, consultants and directors. The plan allows for issuance of up to 1.4 shares of common stock. In addition, as of September 30, 2018, the Company may grant additional shares of common stock under the 2017 Plan with respect to the 0.6 options outstanding under our 2003 Plan and 5.7 options and restricted stock units outstanding under our 2010 Plan, that expire or are cancelled without delivery of shares of common stock. At September 30, 2018, 0.4 shares of common stock were available for issuance under the 2017 Plan. If an RSU awarded under the 2017 Plan is cancelled or forfeited without the issuance of shares of common stock, the unissued or reacquired shares, which were subject to the RSU, shall again be available for issuance pursuant to the 2017 Plan. The number of shares, terms, and vesting periods are determined by the Company’s Board of Directors or a committee thereof on an option-by-option basis. Options generally vest ratably over service periods of four years. Options granted after December 5, 2012 expire eight years from the date of grant, and options granted prior to that date generally expire ten years from the date of grant. In September 2014, the Company began issuing restricted stock units (“RSUs”) in lieu of stock options. RSUs granted to employees generally vest ratably over four years on the anniversary date of the designated day of the last week of the month in which the RSUs are granted. The number of RSUs awarded to certain executive officers may be reduced if certain additional performance metrics are not met. Options and RSUs granted to our non-employee directors vest in full upon completion of one year of service on the Board following the date of the grant. Stock Options A summary of the stock option activity under the Company’s plans for the three months ended September 30, 2018 is as follows: Number of shares Weighted average exercise price Options outstanding at June 30, 2018 6.3 $ 24.50 Options granted — $ — Less: Options exercised (0.6 ) $ 23.84 Options canceled or expired — $ — Options outstanding at September 30, 2018 5.7 $ 24.57 Options exercisable at September 30, 2018 5.7 $ 24.57 As of September 30, 2018, there was no unrecognized share-based compensation expense related to stock options. Restricted Stock Units A summary of the RSU activity under the Company’s plans for the three months ended September 30, 2018 is as follows: Number of shares Weighted average grant date fair value RSUs outstanding at June 30, 2018 2.2 $ 31.12 RSUs granted 1.1 $ 47.81 Less: RSUs vested (0.8 ) $ 32.39 RSUs canceled — $ — RSUs outstanding at September 30, 2018 2.5 $ 38.06 As of September 30, 2018, there was $69.8 of total unrecognized share-based compensation expense related to RSUs that will be recognized over a weighted-average period of 2.7 years. This unrecognized compensation expense is equal to the fair value of RSUs expected to vest. Employee Stock Purchase Plan The Company also has an Employee Stock Purchase Plan that was approved by shareholders in 2012 (the “2012 Purchase Plan”), under which 2.0 shares of common stock have been authorized. Shares are issued under the 2012 Purchase Plan twice yearly at the end of each offering period. As of September 30, 2018, approximately 0.7 shares of common stock have been issued under the 2012 Purchase Plan. Share-Based Compensation Expense Share-based compensation expense recognized and included in the condensed consolidated statements of income and comprehensive income was allocated as follows: Three months ended September 30, 2018 2017 Cost of molecular diagnostic testing $ 0.2 $ 0.2 Cost of pharmaceutical and clinical services 0.1 0.1 Research and development expense 1.2 0.8 Selling, general, and administrative expense 6.2 5.3 Total share-based compensation expense $ 7.7 $ 6.4

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	(13) FAIR VALUE MEASUREMENTS The fair value of the Company’s financial instruments reflects the amounts that the Company estimates it will receive in connection with the sale of an asset or pay in connection with the transfer of a liability in an orderly transaction between market participants at the measurement date (exit price). The fair value of contingent consideration related to the Sividon and Assurex acquisitions as well as the long-term debt were categorized as a level 3 liability, as the measurement amount is based primarily on significant inputs not observable in the market. The fair value hierarchy prioritizes the use of inputs used in valuation techniques into the following three levels: Level 1— quoted prices in active markets for identical assets and liabilities. Level 2— observable inputs other than quoted prices in active markets for identical assets and liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Some of the Company’s marketable securities primarily utilize broker quotes in a non-active market for valuation of these securities. Level 3— unobservable inputs. All of the Company’s financial instruments are valued using quoted prices in active markets or based on other observable inputs. For Level 2 securities, the Company uses a third party pricing service which provides documentation on an ongoing basis that includes, among other things, pricing information with respect to reference data, methodology, inputs summarized by asset class, pricing application and corroborative information. For Level 3 contingent consideration, we reassess the fair value of expected contingent consideration and the corresponding liability each reporting period using the Monte Carlo Method, which is consistent with the initial measurement of the expected earn-out liability. This fair value measurement is considered a Level 3 measurement because we estimate projections during the earn-out period utilizing various potential pay-out scenarios. Probabilities were applied to each potential scenario and the resulting values were discounted using a rate that considers weighted average cost of capital as well as a specific risk premium associated with the riskiness of the earn-out itself, the related projections, and the overall business. The contingent earn-out liabilities are classified as a component of long-term and short-term contingent consideration in our consolidated balance sheets. Changes to these estimated liabilities are reflected in change in the fair value of contingent consideration in our consolidated income statement. Changes to the unobservable inputs could have a material impact on the Company’s financial statements. The fair value of our long-term debt, which we consider a Level 3 measurement, is estimated using discounted cash flow analyses, based on the Company’s current estimated incremental borrowing rates for similar borrowing arrangements. The fair value of long-term debt is estimated to be $209.3 at September 30, 2018. The following table sets forth the fair value of the financial assets and liabilities that the Company re-measures on a regular basis: Level 1 Level 2 Level 3 Total September 30, 2018 Money market funds (a) $ 6.1 $ — $ — $ 6.1 Corporate bonds and notes 3.4 57.3 — 60.7 Municipal bonds — 23.4 — 23.4 Federal agency issues — 9.5 — 9.5 US government securities — 8.2 — 8.2 Contingent consideration — — (14.9 ) (14.9 ) Total $ 9.5 $ 98.4 $ (14.9 ) $ 93.0 (a) Money market funds are primarily comprised of exchange traded funds and accrued interest Level 1 Level 2 Level 3 Total June 30, 2018 Money market funds (a) $ 12.5 $ — $ — $ 12.5 Corporate bonds and notes 2.8 50.5 — 53.3 Municipal bonds — 29.2 — 29.2 Federal agency issues — 12.4 — 12.4 US government securities — 8.3 — 8.3 Contingent consideration — — (14.5 ) (14.5 ) Total $ 15.3 $ 100.4 $ (14.5 ) $ 101.2 (a) Money market funds are primarily comprised of exchange traded funds and accrued interest The following table reconciles the change in the fair value of the contingent consideration during the periods presented: Carrying amount Balance June 30, 2018 $ 14.5 Change in fair value recognized in the income statement 0.4 Ending balance September 30, 2018 $ 14.9

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Sep. 30, 2018
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	(14) COMMITMENTS AND CONTINGENCIES In February 2018, we received a Subpoena from the Department of Health and Human Services, Office of Inspector General, in connection with an investigation into possible false or otherwise improper claims submitted for payment under Medicare and Medicaid. The Subpoena requested that we produce documents relating primarily to our billing to government-funded healthcare programs for our hereditary cancer testing. The time period covered by the Subpoena is January 1, 2014 through the date of issuance of the Subpoena. We are cooperating with the Government’s request and are in the process of responding to the Subpoena. We are unable to predict what action, if any, might be taken in the future by the Government or any other regulatory authority as a result of the matters related to this investigation. No claims have been made against the Company. In addition, the Company is subject to various claims and legal proceedings covering matters that arise in the ordinary course of its business activities. As of September 30, 2018, the management of the Company believes any reasonably possible liability that may result from the resolution of these matters will not have a material adverse effect on the Company’s consolidated financial position, operating results, or cash flows.

Employee Deferred Savings Plan

Employee Deferred Savings Plan	3 Months Ended
	Sep. 30, 2018
Postemployment Benefits [Abstract]
Employee Deferred Savings Plan	(15) EMPLOYEE DEFERRED SAVINGS PLAN The Company has a deferred savings plan which qualifies under Section 401(k) of the Internal Revenue Code. Substantially all of the Company’s U.S. employees are covered by the plan. The Company makes matching contributions of 50% of each employee’s contribution with the employer’s contribution not to exceed 4% of the employee’s compensation. The Company recorded contributions to the plan as follows: Three months ended September 30, 2018 2017 Deferred savings plan contributions $ 2.0 $ 1.9

Segment and Related Information

Segment and Related Information	3 Months Ended
	Sep. 30, 2018
Segment Reporting [Abstract]
Segment and Related Information	(16) SEGMENT AND RELATED INFORMATION The Company’s business is aligned with how the Chief Operating Decision Maker reviews performance and makes decisions in managing the Company. The business units have been aggregated into two reportable segments: (i) diagnostics and (ii) other. The diagnostics segment provides testing and collaborative development of testing that is designed to assess an individual’s risk for developing disease later in life, identify a patient’s likelihood of responding to drug therapy and guide a patient’s dosing to ensure optimal treatment, or assess a patient’s risk of disease progression and disease recurrence. The other segment provides testing products and services to the pharmaceutical, biotechnology and medical research industries, research and development, and clinical services for patients, and includes corporate services such as finance, human resources, legal and information technology. Segment revenue and operating income (loss) were as follows during the periods presented: Diagnostics Other Total Three months ended September 30, 2018 Revenues $ 189.0 $ 13.3 $ 202.3 Depreciation and amortization 17.0 1.3 18.3 Segment operating income (loss) 27.6 (26.4 ) 1.2 Three months ended September 30, 2017 Revenues $ 167.4 $ 11.4 $ 178.8 Depreciation and amortization 11.8 1.4 13.2 Segment operating income 30.6 53.4 84.0 Three months ended September 30, 2018 2017 Total operating income for reportable segments $ 1.2 $ 84.0 Unallocated amounts: Interest income 0.7 0.4 Interest expense (2.2 ) (0.9 ) Other 1.1 (0.3 ) Income from operations before income taxes 0.8 83.2 Income tax provision 1.6 4.5 Net income (loss) (0.8 ) 78.7 Net loss attributable to non-controlling interest (0.1 ) (0.1 ) Net income (loss) attributable to Myriad Genetics, Inc. stockholders $ (0.7 ) $ 78.8

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	3 Months Ended
	Sep. 30, 2018
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information	(17) SUPPLEMENTAL CASH FLOW INFORMATION Three months ended September 30, 2018 2017 Cash paid during the period for income taxes $ 4.9 $ 5.2 Cash paid for interest $ (0.9 ) $ (1.0 )

Basis of Presentation (Policies

Basis of Presentation (Policies)	3 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation	The accompanying condensed consolidated financial statements have been prepared by Myriad Genetics, Inc. (the “Company” or “Myriad”) in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and pursuant to the applicable rules and regulations of the Securities and Exchange Commission (“SEC”). The condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation. In the opinion of management, the accompanying financial statements contain all adjustments (consisting of normal and recurring accruals) necessary to present fairly all financial statements in accordance with GAAP. The condensed consolidated financial statements herein should be read in conjunction with the Company’s audited consolidated financial statements and notes thereto for the fiscal year ended June 30, 2018, included in the Company’s Annual Report on Form 10-K for the fiscal year ended June 30, 2018. Operating results for the three months ended September 30, 2018 may not necessarily be indicative of results to be expected for any other interim period or for the full year. The consolidated financial statements include the accounts of the Company’s majority-owned subsidiary, Assurex Canada, Ltd. which is 85% owned by Assurex Health, Inc. (“Assurex”), a wholly owned subsidiary of the Company, and 15% owned by the Centre for Addiction and Mental Health. Assurex Canada, Ltd. is a consolidated subsidiary of Assurex Health, Inc. The value of the non-controlling interest represents the portion of Assurex Canada, Ltd.’s profit or loss and net assets that is not held by Assurex Health, Inc. The Company attributes comprehensive income or loss of the subsidiary between the Company and the non-controlling interest based on the respective ownership interest. The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements, as well as the reported amounts of revenue and expenses during the reporting period. Actual results could differ from those estimates.
New Accounting Pronouncements	New Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (FASB) issued the converged standard on revenue recognition with the objective of providing a single, comprehensive model for all contracts with customers to improve comparability in the financial statements of companies reporting using International Financial Reporting Standards and U.S. GAAP. The standard contains principles that an entity must apply to determine the measurement of revenue and timing of when it is recognized. The underlying principle is that an entity must recognize revenue to depict the transfer of goods or services to customers at an amount that the entity expects to be entitled to in exchange for those goods or services. An entity can apply the revenue standard retrospectively to each prior reporting period presented (full retrospective method) or retrospectively with the cumulative effect of initially applying the standard recognized at the date of initial application in retained earnings (modified retrospective method). The standard was effective for the Company beginning July 1, 2018. The Company elected to adopt the standard using the full retrospective approach, which resulted in a recasting of revenue and the related financial statement items for FY2017 and FY2018. During transition to the new standard, the Company also elected several practical expedients, as provided by the standard. Contracts that began and ended within the same annual reporting period were not restated. Contracts that were completed by June 30, 2018 that had variable consideration were estimated using the transaction price at the date the contract was completed. The amount of the transaction price allocated to the remaining performance obligations will not be disclosed for prior reporting periods. Contracts that were modified prior to the earliest reporting period will be reflected in the earliest reporting period with an aggregate adjustment for prior modifications. As a result of the new standard, the Company has changed its accounting policies for revenue recognition. The primary impact of the new standard was classifying bad debt expense of $8.0 for the three months ended September 30, 2017, as a reduction in revenue rather than as a selling, general and administrative expense. The Company also increased its June 30, 2018 accounts receivable and retained earnings balances by $1.2 as a result of adopting the new standard. Reclassifications Adoption of new revenue recognition standard impacted the Company’s previously reported results as follows: Three months ended September 30, 2017 As Previously Reported ASC606 Adjustments As Restated Consolidated Statements of Operations: Total Revenue $ 187.9 $ (9.1 ) $ 178.8 Selling, general and administrative expense 115.2 (8.0 ) 107.2 Income tax provision 4.8 (0.3 ) 4.5 Net Income attributable to Myriad Genetics, Inc. stockholders 79.6 (0.8 ) 78.8 Earnings per share: Basic $ 1.16 $ (0.01 ) $ 1.15 Diluted $ 1.13 $ (0.01 ) $ 1.12 Consolidated Statements of Cash Flows: Net Income attributable to Myriad Genetics, Inc. stockholders 79.6 (0.8 ) $ 78.8 Trade Accounts Receivable (16.5 ) 10.3 (6.2 ) June 30, 2018 As Previously Reported ASC606 Adjustments As Restated Consolidated Balance Sheet: Trade accounts receivable $ 98.3 $ 1.2 $ 99.5 Retained Earnings 52.9 1.2 54.1 In February 2016, the FASB issued Accounting Standards Update (“ASU”) 2016-02, Leases. ASU 2016-02 amends the existing accounting standards for lease accounting, including requiring lessees to recognize most leases on their balance sheets and making targeted changes to lessor accounting. ASU 2016-02 will be effective beginning in the first quarter of fiscal 2020. Early adoption of ASU 2016-02 is permitted. ASU 2016-02 requires a modified retrospective transition approach for all leases existing at, or entered into after, the date of initial application, with an option to use certain transition relief. The Company’s management is currently evaluating the impact of adopting ASU 2016-02 on the Company’s consolidated financial statements. In accordance with the Securities Act Release No. 33-10532 which now requires presenting changes in stockholders equity quarterly we have included our condensed consolidated statements of equity.

Basis of Presentation (Tables)

Basis of Presentation (Tables)	3 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Adoption of New Revenue Recognition Standard Revenue Impacted Previously Reported	Adoption of new revenue recognition standard impacted the Company’s previously reported results as follows: Three months ended September 30, 2017 As Previously Reported ASC606 Adjustments As Restated Consolidated Statements of Operations: Total Revenue $ 187.9 $ (9.1 ) $ 178.8 Selling, general and administrative expense 115.2 (8.0 ) 107.2 Income tax provision 4.8 (0.3 ) 4.5 Net Income attributable to Myriad Genetics, Inc. stockholders 79.6 (0.8 ) 78.8 Earnings per share: Basic $ 1.16 $ (0.01 ) $ 1.15 Diluted $ 1.13 $ (0.01 ) $ 1.12 Consolidated Statements of Cash Flows: Net Income attributable to Myriad Genetics, Inc. stockholders 79.6 (0.8 ) $ 78.8 Trade Accounts Receivable (16.5 ) 10.3 (6.2 ) June 30, 2018 As Previously Reported ASC606 Adjustments As Restated Consolidated Balance Sheet: Trade accounts receivable $ 98.3 $ 1.2 $ 99.5 Retained Earnings 52.9 1.2 54.1

Revenue (Tables)

Revenue (Tables)	3 Months Ended
	Sep. 30, 2018
Revenue From Contract With Customer [Abstract]
Composition of Total Revenue by Product and U.S versus Rest of World	The following table presents detail regarding the composition of our total revenue by product and U.S versus rest of world, “RoW”: Three months ended September 30, 2018 2017 (In millions) U.S. RoW Total U.S. RoW Total Molecular diagnostic revenues: Hereditary Cancer Testing $ 113.5 $ 2.8 $ 116.3 $ 114.6 $ 2.4 $ 117.0 GeneSight 29.3 29.3 28.8 28.8 Prenatal 18.1 — 18.1 — — — VectraDA 13.0 — 13.0 14.0 — 14.0 Prolaris 6.2 — 6.2 3.9 — 3.9 EndoPredict 0.3 2.1 2.4 0.0 1.8 1.8 Other 3.6 0.1 3.7 1.8 0.1 1.9 Total molecular diagnostic revenue 184.0 5.0 189.0 163.1 4.3 167.4 Pharmaceutical and clinical service revenue 7.6 5.7 13.3 6.3 5.1 11.4 Total revenue $ 191.6 $ 10.7 $ 202.3 $ 169.4 $ 9.4 $ 178.8
Reconciliation of Deferred Revenue Balances	A reconciliation of the beginning and ending balances of deferred revenue is shown in the table below: Three months ended September 30, 2018 2017 Deferred revenue - beginning balance $ 2.6 $ 2.6 Revenue recognized (1.7 ) (5.9 ) Prepayments 1.6 6.2 Deferred revenue - Ending Balance $ 2.5 $ 2.9

Acquisitions (Tables)

Acquisitions (Tables)	3 Months Ended
	Sep. 30, 2018
Pro Forma Results of Acquisitions	Accordingly, these unaudited pro forma results are presented for informational purposes only and are not necessarily indicative of what the actual results of operation of the combined company would have been if the acquisition had occurred at the beginning of the period presented nor are they indicative of future results of operations and are not necessarily indicative of results that might have been achieved had the acquisition been consummated as of July 1, 2017. Three months ended September 30, 2018 2017 Revenue $ 212.5 $ 209.5 Income from operations 11.5 69.6 Net income 8.6 61.3 Net income per share, basic $ 0.11 $ 0.86 Net income per share, diluted $ 0.11 $ 0.84
Counsyl Inc [Member]
Allocation of Consideration Transferred	The Company expects the allocation of the consideration transferred to be final within the measurement period (up to one year from the acquisition date). Estimated Fair Value Current assets $ 42.5 Intangible assets 292.9 Equipment 18.9 Other assets 0.1 Goodwill 94.9 Current liabilities (19.6 ) Long term liabilities (0.1 ) Deferred tax liability (7.3 ) Total fair value purchase price $ 422.3 Less: Cash acquired (15.3 ) Total consideration transferred $ 407.0

Marketable Investment Securit_2

Marketable Investment Securities (Tables)	3 Months Ended
	Sep. 30, 2018
Investments Debt And Equity Securities [Abstract]
Schedule of Fair Value for Available-for-Sale Securities by Major Security Type and Class of Security	The amortized cost, gross unrealized holding gains, gross unrealized holding losses, and fair value for available-for-sale securities by major security type and class of security at September 30, 2018 and June 30, 2018 were as follows: Gross Gross unrealized unrealized Amortized holding holding Estimated cost gains losses fair value At September 30, 2018: Cash and cash equivalents: Cash $ 75.3 $ — $ — $ 75.3 Cash equivalents 18.0 — — $ 18.0 Total cash and cash equivalents 93.3 — — 93.3 Available-for-sale: Corporate bonds and notes 57.5 — (0.3 ) 57.2 Municipal bonds 23.4 — (0.1 ) 23.3 Federal agency issues 9.6 — — 9.6 US government securities 8.3 — — 8.3 Total $ 192.1 $ — $ (0.4 ) $ 191.7 Gross Gross unrealized unrealized Amortized holding holding Estimated cost gains losses fair value At June 30, 2018: Cash and cash equivalents: Cash $ 95.6 $ — $ — $ 95.6 Cash equivalents 15.3 — — 15.3 Total cash and cash equivalents 110.9 — — 110.9 Available-for-sale: Corporate bonds and notes 50.8 — (0.3 ) 50.5 Municipal bonds 29.3 — (0.1 ) 29.2 Federal agency issues 12.6 — (0.1 ) 12.5 US government securities 8.3 — (0.1 ) 8.2 Total $ 211.9 $ — $ (0.6 ) $ 211.3
Schedule of Maturities of Debt Securities Classified as Cash Equivalents and Available-For-Sale Securities	Cash, cash equivalents, and maturities of debt securities classified as available-for-sale securities are as follows at September 30, 2018: Amortized Estimated cost fair value Cash $ 75.3 $ 75.3 Cash equivalents 18.0 18.0 Available-for-sale: Due within one year 75.9 75.6 Due after one year through five years 22.9 22.8 Due after five years — — Total $ 192.1 $ 191.7

Property, Plant and Equipment_2

Property, Plant and Equipment, Net (Tables)	3 Months Ended
	Sep. 30, 2018
Property Plant And Equipment [Abstract]
Schedule of Property, Plant and Equipment, Net	September 30, June 30, 2018 2018 Land $ 2.4 $ 2.4 Buildings and improvements 19.2 19.3 Leasehold improvements 29.9 23.0 Equipment 113.0 112.4 164.5 157.1 Less accumulated depreciation (104.5 ) (113.9 ) Property, plant and equipment, net $ 60.0 $ 43.2 Three months ended September 30, 2018 2017 Depreciation expense $ 4.9 $ 3.9

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	3 Months Ended
	Sep. 30, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Changes in Carrying Amount of Goodwill	The following summarizes changes to the goodwill balance for the three months ended September 30, 2018 Carrying amount Beginning balance July 1, 2018 $ 318.6 Acquisitions 94.9 Translation adjustments (0.2 ) Ending balance September 30, 2018 $ 413.3
Summarized Amounts Reported as Intangible Assets	The following summarizes the amounts reported as intangible assets Gross Carrying Accumulated Amount Amortization Net At September 30, 2018: Purchased licenses and technologies $ 819.1 $ (111.4 ) $ 707.7 Customer relationships 4.6 (3.4 ) 1.2 Trademarks 3.0 (1.0 ) 2.0 Total amortized intangible assets 826.7 (115.8 ) 710.9 In-process research and development 23.3 — 23.3 Total unamortized intangible assets 23.3 — 23.3 Total intangible assets $ 850.0 $ (115.8 ) $ 734.2 Gross Carrying Accumulated Amount Amortization Net At June 30, 2018: Purchased licenses and technologies $ 526.4 $ (98.0 ) $ 428.4 Customer relationships 4.6 (3.3 ) 1.3 Trademarks 3.0 (1.0 ) 2.0 Total amortized intangible assets 534.0 (102.3 ) 431.7 In-process research and development 23.5 — 23.5 Total unamortized intangible assets 23.5 — 23.5 Total intangible assets $ 557.5 $ (102.3 ) $ 455.2
Amortization for Intangible Assets	The Company recorded amortization expense during the respective periods for these intangible assets as follows: Three months ended September 30, 2018 2017 Amortization of intangible assets $ 13.4 $ 9.3

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	3 Months Ended
	Sep. 30, 2018
Payables And Accruals [Abstract]
Summary of Accrued Liabilities	September 30, June 30, 2018 2018 Employee compensation and benefits $ 47.8 $ 49.5 Accrued taxes payable 9.8 4.3 Other 18.8 14.5 Total accrued liabilities $ 76.4 $ 68.3

Long-Term Debt (Tables)

Long-Term Debt (Tables)	3 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Schedule of Long-Term Debt	Amounts outstanding under the Amended Facility and Facility were as follows: September 30, June 30, 2018 2018 Long-term debt $ 260.1 $ 10.0 Long-term debt discount (2.1 ) (0.7 ) Net long-term debt $ 258.0 $ 9.3

Other Long Term Liabilities (Ta

Other Long Term Liabilities (Tables)	3 Months Ended
	Sep. 30, 2018
Other Liabilities Disclosure [Abstract]
Summary of Other Long Term Liabilities	September 30, June 30, 2018 2018 Pension obligation 6.1 6.0 Other 0.2 0.3 Total other long term liabilities $ 6.3 $ 6.3

Preferred and Common Stockhol_2

Preferred and Common Stockholder's Equity (Tables)	3 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Summary of Common Shares Issued and Outstanding	Common shares issued and outstanding Three months ended Year ended September 30, June 30, 2018 2018 Common stock issued and outstanding at July 1 70.6 68.4 Common stock issued upon exercise of options and employee stock plans 4.1 2.2 Repurchase and retirement of common stock — — Common stock issued and outstanding at end of period 74.7 70.6
Reconciliation of Denominators of Basic and Diluted Earnings Per Share Computations	The following is a reconciliation of the denominators of the basic and diluted earnings per share (“EPS”) computations: Three months ended September 30, 2018 2017 Denominator: Weighted-average shares outstanding used to compute basic EPS 73.0 68.6 Effect of dilutive shares — 1.8 Weighted-average shares outstanding and dilutive securities used to compute diluted EPS 73.0 70.4
Schedule of Anti-Dilutive Options and Restricted Stock Units Excluded from EPS Computation	These potential dilutive common shares, which may be dilutive to future diluted earnings per share, are as follows: Three months ended September 30, 2018 2017 Anti-dilutive options and RSU's excluded from EPS computation 4.1 1.5
Schedule of Stock Repurchases	The shares retired, aggregate common stock and additional paid-in capital reductions, and related charges to accumulated deficit for the repurchases for periods ended September 30, 2018 and 2017 were as follows: Three months ended September 30, 2018 2017 Shares purchased and retired — — Common stock and additional paid-in-capital reductions $ — $ — Charges to retained earnings $ — $ —

Share-Based Compensation (Table

Share-Based Compensation (Tables)	3 Months Ended
	Sep. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Schedule of Share-Based Compensation Arrangement by Share Based Payment Award Options Outstanding	A summary of the stock option activity under the Company’s plans for the three months ended September 30, 2018 is as follows: Number of shares Weighted average exercise price Options outstanding at June 30, 2018 6.3 $ 24.50 Options granted — $ — Less: Options exercised (0.6 ) $ 23.84 Options canceled or expired — $ — Options outstanding at September 30, 2018 5.7 $ 24.57 Options exercisable at September 30, 2018 5.7 $ 24.57
Schedule of Share-Based Compensation Arrangement by Share Based Payment Award Restricted Stock Units Outstanding	A summary of the RSU activity under the Company’s plans for the three months ended September 30, 2018 is as follows: Number of shares Weighted average grant date fair value RSUs outstanding at June 30, 2018 2.2 $ 31.12 RSUs granted 1.1 $ 47.81 Less: RSUs vested (0.8 ) $ 32.39 RSUs canceled — $ — RSUs outstanding at September 30, 2018 2.5 $ 38.06
Schedule of Share-Based Compensation Recognized in Consolidated Statements of Operations	Share-based compensation expense recognized and included in the condensed consolidated statements of income and comprehensive income was allocated as follows: Three months ended September 30, 2018 2017 Cost of molecular diagnostic testing $ 0.2 $ 0.2 Cost of pharmaceutical and clinical services 0.1 0.1 Research and development expense 1.2 0.8 Selling, general, and administrative expense 6.2 5.3 Total share-based compensation expense $ 7.7 $ 6.4

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Schedule of Fair Value of Financial Assets and Liabilities	The following table sets forth the fair value of the financial assets and liabilities that the Company re-measures on a regular basis: Level 1 Level 2 Level 3 Total September 30, 2018 Money market funds (a) $ 6.1 $ — $ — $ 6.1 Corporate bonds and notes 3.4 57.3 — 60.7 Municipal bonds — 23.4 — 23.4 Federal agency issues — 9.5 — 9.5 US government securities — 8.2 — 8.2 Contingent consideration — — (14.9 ) (14.9 ) Total $ 9.5 $ 98.4 $ (14.9 ) $ 93.0 (a) Money market funds are primarily comprised of exchange traded funds and accrued interest Level 1 Level 2 Level 3 Total June 30, 2018 Money market funds (a) $ 12.5 $ — $ — $ 12.5 Corporate bonds and notes 2.8 50.5 — 53.3 Municipal bonds — 29.2 — 29.2 Federal agency issues — 12.4 — 12.4 US government securities — 8.3 — 8.3 Contingent consideration — — (14.5 ) (14.5 ) Total $ 15.3 $ 100.4 $ (14.5 ) $ 101.2 (a) Money market funds are primarily comprised of exchange traded funds and accrued interest
Change in Fair Value of Contingent Consideration	The following table reconciles the change in the fair value of the contingent consideration during the periods presented: Carrying amount Balance June 30, 2018 $ 14.5 Change in fair value recognized in the income statement 0.4 Ending balance September 30, 2018 $ 14.9

Employee Deferred Savings Plan

Employee Deferred Savings Plan (Tables)	3 Months Ended
	Sep. 30, 2018
Postemployment Benefits [Abstract]
Recorded Contributions to Employee Deferred Savings Plan	The Company recorded contributions to the plan as follows: Three months ended September 30, 2018 2017 Deferred savings plan contributions $ 2.0 $ 1.9

Segment and Related Informati_2

Segment and Related Information (Tables)	3 Months Ended
	Sep. 30, 2018
Segment Reporting [Abstract]
Schedule of Segment Performance Based on Income (Loss) before Interest Income and Other Income and Expense	Segment revenue and operating income (loss) were as follows during the periods presented: Diagnostics Other Total Three months ended September 30, 2018 Revenues $ 189.0 $ 13.3 $ 202.3 Depreciation and amortization 17.0 1.3 18.3 Segment operating income (loss) 27.6 (26.4 ) 1.2 Three months ended September 30, 2017 Revenues $ 167.4 $ 11.4 $ 178.8 Depreciation and amortization 11.8 1.4 13.2 Segment operating income 30.6 53.4 84.0 Three months ended September 30, 2018 2017 Total operating income for reportable segments $ 1.2 $ 84.0 Unallocated amounts: Interest income 0.7 0.4 Interest expense (2.2 ) (0.9 ) Other 1.1 (0.3 ) Income from operations before income taxes 0.8 83.2 Income tax provision 1.6 4.5 Net income (loss) (0.8 ) 78.7 Net loss attributable to non-controlling interest (0.1 ) (0.1 ) Net income (loss) attributable to Myriad Genetics, Inc. stockholders $ (0.7 ) $ 78.8

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information (Tables)	3 Months Ended
	Sep. 30, 2018
Supplemental Cash Flow Elements [Abstract]
Schedule of Supplemental Cash Flow Information	Three months ended September 30, 2018 2017 Cash paid during the period for income taxes $ 4.9 $ 5.2 Cash paid for interest $ (0.9 ) $ (1.0 )

Basis of Presentation - Additio

Basis of Presentation - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2017	Sep. 30, 2018	Jun. 30, 2018
ASC 606
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Reduction in revenue classified as bad debt expense	$ 8
Increased accounts receivable and retained earnings balances			$ 1.2
Assurex [Member]
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Non controlling interest ownership percentage by parent		85.00%
Centre For Addiction And Mental Health [Member]
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Non controlling interest ownership percentage by noncontrolling owners		15.00%

Basis of Presentation - Adoptio

Basis of Presentation - Adoption of New Revenue Recognition Standard Revenue Impacted Previously Reported (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Jun. 30, 2018
Consolidated Statements of Operations:
Total revenue	$ 202.3	$ 178.8
Selling, general, and administrative expense	129.9	107.2
Income tax provision	1.6	4.5
Net income (loss) attributable to Myriad Genetics, Inc. stockholders	$ (0.7)	$ 78.8
Earnings per share:
Basic	$ (0.01)	$ 1.15
Diluted	$ (0.01)	$ 1.12
Consolidated Statements of Cash Flows:
Net income (loss) attributable to Myriad Genetics, Inc. stockholders	$ (0.7)	$ 78.8
Trade accounts receivable	(3.3)	(6.2)
Consolidated Balance Sheet:
Trade accounts receivable	119.1		$ 99.5
Retained earnings	$ 53.4		54.1
ASC 606 | As Previously Reported
Consolidated Statements of Operations:
Total revenue		187.9
Selling, general, and administrative expense		115.2
Income tax provision		4.8
Net income (loss) attributable to Myriad Genetics, Inc. stockholders		$ 79.6
Earnings per share:
Basic		$ 1.16
Diluted		$ 1.13
Consolidated Statements of Cash Flows:
Net income (loss) attributable to Myriad Genetics, Inc. stockholders		$ 79.6
Trade accounts receivable		(16.5)
Consolidated Balance Sheet:
Trade accounts receivable			98.3
Retained earnings			52.9
ASC 606 | Adjustments
Consolidated Statements of Operations:
Total revenue		(9.1)
Selling, general, and administrative expense		(8)
Income tax provision		(0.3)
Net income (loss) attributable to Myriad Genetics, Inc. stockholders		$ (0.8)
Earnings per share:
Basic		$ (0.01)
Diluted		$ (0.01)
Consolidated Statements of Cash Flows:
Net income (loss) attributable to Myriad Genetics, Inc. stockholders		$ (0.8)
Trade accounts receivable		$ 10.3
Consolidated Balance Sheet:
Trade accounts receivable			1.2
Retained earnings			$ 1.2

Revenue - Composition of Total

Revenue - Composition of Total Revenue by Product and U.S versus Rest of World (Detail) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Disaggregation Of Revenue [Line Items]
Total revenue	$ 202.3	$ 178.8
U.S. [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	191.6	169.4
RoW [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	10.7	9.4
Molecular Diagnostic - Hereditary Cancer Testing [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	116.3	117
Molecular Diagnostic - Hereditary Cancer Testing [Member] | U.S. [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	113.5	114.6
Molecular Diagnostic - Hereditary Cancer Testing [Member] | RoW [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	2.8	2.4
Molecular Diagnostic - GeneSight [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	29.3	28.8
Molecular Diagnostic - GeneSight [Member] | U.S. [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	29.3	28.8
Molecular Diagnostic - Prenatal [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	18.1
Molecular Diagnostic - Prenatal [Member] | U.S. [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	18.1
Molecular Diagnostic- VectraDA [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	13	14
Molecular Diagnostic- VectraDA [Member] | U.S. [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	13	14
Molecular Diagnostic - Prolaris [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	6.2	3.9
Molecular Diagnostic - Prolaris [Member] | U.S. [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	6.2	3.9
Molecular Diagnostic - EndoPredict [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	2.4	1.8
Molecular Diagnostic - EndoPredict [Member] | U.S. [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	0.3	0
Molecular Diagnostic - EndoPredict [Member] | RoW [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	2.1	1.8
Molecular Diagnostic - Other [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	3.7	1.9
Molecular Diagnostic - Other [Member] | U.S. [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	3.6	1.8
Molecular Diagnostic - Other [Member] | RoW [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	0.1	0.1
Molecular Diagnostic Testing [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	189	167.4
Molecular Diagnostic Testing [Member] | U.S. [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	184	163.1
Molecular Diagnostic Testing [Member] | RoW [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	5	4.3
Pharmaceutical and Clinical Services [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	13.3	11.4
Pharmaceutical and Clinical Services [Member] | U.S. [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	7.6	6.3
Pharmaceutical and Clinical Services [Member] | RoW [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	$ 5.7	$ 5.1

Revenue - Reconciliation of Def

Revenue - Reconciliation of Deferred Revenue Balances (Detail) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Revenue From Contract With Customer [Abstract]
Deferred revenue - beginning balance	$ 2.6	$ 2.6
Revenue recognized	(1.7)	(5.9)
Prepayments	1.6	6.2
Deferred revenue - Ending Balance	$ 2.5	$ 2.9

Revenue - Additional Informatio

Revenue - Additional Information (Detail)	3 Months Ended
	Sep. 30, 2018USD ($)
Disaggregation Of Revenue [Line Items]
Revenue, practical expedient, remaining performance obligation, description	In accordance with ASU 2014-09, the Company has elected not to disclose the aggregate amount of the transaction price allocated to remaining performance obligations for its contracts that are one year or less, as the revenue is expected to be recognized within the next year. Furthermore, the Company has elected not to disclose the aggregate amount of the transaction price allocated to remaining performance obligations for its agreements wherein the Company’s right to payment is in an amount that directly corresponds with the value of Company’s performance to date. However, periodically the Company enters into arrangements with customers to provide diagnostic testing and/or pharmaceutical and clinical services that may have terms longer than one year and include multiple performance obligations.
Revenue, practical expedient, remaining performance obligation	true
Revenue, practical expedient, initial application and transition, nondisclosure of transaction price allocation to remaining performance obligation	true
Revenue, remaining performance obligation	$ 7,300,000
Capitalized costs incurred to obtain or fulfill contract	$ 0
Revenue practical expedient, incremental cost of obtaining contract	true
Revenue, performance obligation, description of payment terms	This practical expedient has been elected because the Company collects very little cash from customers under payment terms and vast majority of payments terms have a payback period of less than one year.

Revenue - Additional Informat_2

Revenue - Additional Information (Detail 1) $ in Millions	Sep. 30, 2018USD ($)
Disaggregation Of Revenue [Line Items]
Revenue, remaining performance obligation	$ 7.3
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2018-07-01
Disaggregation Of Revenue [Line Items]
Revenue, remaining performance obligation	$ 4.3
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year

Acquisitions - Additional Infor

Acquisitions - Additional Information (Detail) $ / shares in Units, $ in Millions	Jul. 31, 2018USD ($)$ / sharesshares	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)
Business Acquisition [Line Items]
Goodwill		$ 413.3	$ 318.6
Counsyl Inc [Member]
Business Acquisition [Line Items]
Business acquisition consideration	$ 407
Acquired intangible assets	292.9
Goodwill	$ 94.9
Acquisition costs		6.8
Revenue contributed by acquired entity		19.4
Operating expenses related to acquired entity		$ 33
Counsyl Inc [Member] | Measurement Input, Discount Rate [Member]
Business Acquisition [Line Items]
Estimated net cash flows, discount rate	12.5
Counsyl Inc [Member] | Developed Screening Processes [Member]
Business Acquisition [Line Items]
Acquired intangible assets	$ 292
Intangible assets estimated useful lives	12 years
Counsyl Inc [Member] | Internally Developed Software [Member]
Business Acquisition [Line Items]
Acquired intangible assets	$ 0.9
Intangible assets estimated useful lives	5 years
Counsyl Inc [Member] | Agreement and Plan of Merger [Member]
Business Acquisition [Line Items]
Effective date of business acquisition	Jul. 31, 2018
Business acquisition consideration	$ 407
Cash payment on business acquisition	279.6
Amount of cash consideration deposited in escrow account	$ 5
Counsyl Inc [Member] | Agreement and Plan of Merger [Member] | Common Stock [Member]
Business Acquisition [Line Items]
Business acquisition, shares issued | shares	2,994,251
Business acquisition, shares issued, value	$ 127.4
Business acquisition, per share market closing price | $ / shares	$ 42.53

Acquisitions - Allocation of Co

Acquisitions - Allocation of Consideration Transferred (Detail) - USD ($) $ in Millions	Jul. 31, 2018	Sep. 30, 2018	Jun. 30, 2018
Business Acquisition [Line Items]
Goodwill		$ 413.3	$ 318.6
Counsyl Inc [Member]
Business Acquisition [Line Items]
Current assets	$ 42.5
Intangible assets	292.9
Equipment	18.9
Other assets	0.1
Goodwill	94.9
Current liabilities	(19.6)
Long term liabilities	(0.1)
Deferred tax liability	(7.3)
Total fair value purchase price	422.3
Less: Cash acquired	(15.3)
Total consideration transferred	$ 407

Acquisitions - Pro Forma Result

Acquisitions - Pro Forma Results of Acquisitions (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Business Combinations [Abstract]
Revenue	$ 212.5	$ 209.5
Income from operations	11.5	69.6
Net income	$ 8.6	$ 61.3
Net income per share, basic	$ 0.11	$ 0.86
Net income per share, diluted	$ 0.11	$ 0.84

Marketable Investment Securit_3

Marketable Investment Securities - Schedule of Fair Value for Available-for-Sale Securities by Major Security Type and Class of Security (Detail) - USD ($) $ in Millions	Sep. 30, 2018	Jun. 30, 2018	Sep. 30, 2017	Jun. 30, 2017
Schedule of Available-for-sale Securities [Line Items]
Cash and cash equivalents, Amortized cost	$ 93.3	$ 110.9	$ 87.9	$ 102.4
Available-for-sale, Amortized cost	192.1	211.9
Gross unrealized holding losses	(0.4)	(0.6)
Available-for-sale, Estimated fair value	191.7	211.3
Amortized cost	192.1	211.9
Estimated fair value	191.7	211.3
Cash [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and cash equivalents, Amortized cost	75.3	95.6
Cash and cash equivalents, Estimated fair value	75.3	95.6
Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and cash equivalents, Amortized cost	18	15.3
Cash and cash equivalents, Estimated fair value	18	15.3
Total Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and cash equivalents, Amortized cost	93.3	110.9
Cash and cash equivalents, Estimated fair value	93.3	110.9
Corporate Bonds and Notes [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale, Amortized cost	57.5	50.8
Gross unrealized holding losses	(0.3)	(0.3)
Available-for-sale, Estimated fair value	57.2	50.5
Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale, Amortized cost	23.4	29.3
Gross unrealized holding losses	(0.1)	(0.1)
Available-for-sale, Estimated fair value	23.3	29.2
Federal Agency Issues [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale, Amortized cost	9.6	12.6
Gross unrealized holding losses		(0.1)
Available-for-sale, Estimated fair value	9.6	12.5
US Government Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale, Amortized cost	8.3	8.3
Gross unrealized holding losses		(0.1)
Available-for-sale, Estimated fair value	$ 8.3	$ 8.2

Marketable Investment Securit_4

Marketable Investment Securities - Schedule of Maturities of Debt Securities Classified as Cash Equivalents and Available-For-Sale Securities (Detail) - USD ($) $ in Millions	Sep. 30, 2018	Jun. 30, 2018	Sep. 30, 2017	Jun. 30, 2017
Schedule of Available-for-sale Securities [Line Items]
Cash and cash equivalents, Amortized cost	$ 93.3	$ 110.9	$ 87.9	$ 102.4
Due within one year, Amortized cost	75.9
Due after one year through five years, Amortized cost	22.9
Due after five years, Amortized cost	0
Total, Amortized cost	192.1	211.9
Due within one year, Estimated fair value	75.6
Due after one year through five years, Estimated fair value	22.8
Due after five years, Estimated fair value	0
Total, Estimated fair value	191.7	211.3
Cash [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and cash equivalents, Amortized cost	75.3	95.6
Cash equivalents, Estimated fair value	75.3	95.6
Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and cash equivalents, Amortized cost	18	15.3
Cash equivalents, Estimated fair value	$ 18	$ 15.3

Property, Plant and Equipment_3

Property, Plant and Equipment, Net - Schedule of Property, Plant and Equipment, Net (Detail) - USD ($) $ in Millions	Sep. 30, 2018	Jun. 30, 2018
Property Plant And Equipment [Abstract]
Land	$ 2.4	$ 2.4
Buildings and improvements	19.2	19.3
Leasehold improvements	29.9	23
Equipment	113	112.4
Gross property, plant and equipment	164.5	157.1
Less accumulated depreciation	(104.5)	(113.9)
Property, plant and equipment, net	$ 60	$ 43.2

Property, Plant and Equipment_4

Property, Plant and Equipment, Net - Schedule of Depreciation Expense (Detail) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Property Plant And Equipment [Abstract]
Depreciation expense	$ 4.9	$ 3.9

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets - Additional Information (Detail) - USD ($) $ in Millions	Sep. 30, 2018	Jun. 30, 2018
Goodwill And Intangible Assets [Line Items]
Goodwill	$ 413.3	$ 318.6
Diagnostics [Member]
Goodwill And Intangible Assets [Line Items]
Goodwill	347.5
Other [Member]
Goodwill And Intangible Assets [Line Items]
Goodwill	$ 65.8

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Summary of Changes to Goodwill Balance (Detail) $ in Millions	3 Months Ended
	Sep. 30, 2018USD ($)
Goodwill And Intangible Assets Disclosure [Abstract]
Beginning balance	$ 318.6
Acquisitions	94.9
Translation adjustments	(0.2)
Ending balance	$ 413.3

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets - Summarized Amounts Reported as Intangible Assets (Detail) - USD ($) $ in Millions	Sep. 30, 2018	Jun. 30, 2018
Intangible Assets [Line Items]
Gross Carrying Amount, amortized intangible assets	$ 826.7	$ 534
Gross Carrying Amount, total intangible assets	850	557.5
Accumulated Amortization	(115.8)	(102.3)
Net, amortized intangible assets	710.9	431.7
Net, total intangible assets	734.2	455.2
Net, non-amortizable intangible assets	23.3	23.5
In-Process Research and Development [Member]
Intangible Assets [Line Items]
Net, non-amortizable intangible assets	23.3	23.5
Purchased Licenses and Technologies [Member]
Intangible Assets [Line Items]
Gross Carrying Amount, amortized intangible assets	819.1	526.4
Accumulated Amortization	(111.4)	(98)
Net, amortized intangible assets	707.7	428.4
Customer Relationships [Member]
Intangible Assets [Line Items]
Gross Carrying Amount, amortized intangible assets	4.6	4.6
Accumulated Amortization	(3.4)	(3.3)
Net, amortized intangible assets	1.2	1.3
Trademarks [Member]
Intangible Assets [Line Items]
Gross Carrying Amount, amortized intangible assets	3	3
Accumulated Amortization	(1)	(1)
Net, amortized intangible assets	$ 2	$ 2

Goodwill and Intangible Asset_5

Goodwill and Intangible Assets - Amortization on Intangible Assets (Detail) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
Amortization of intangible assets	$ 13.4	$ 9.3

Accrued Liabilities - Summary o

Accrued Liabilities - Summary of Accrued Liabilities (Detail) - USD ($) $ in Millions	Sep. 30, 2018	Jun. 30, 2018
Payables And Accruals [Abstract]
Employee compensation and benefits	$ 47.8	$ 49.5
Accrued taxes payable	9.8	4.3
Other	18.8	14.5
Total accrued liabilities	$ 76.4	$ 68.3

Long Term Debt - Additional Inf

Long Term Debt - Additional Information (Detail) - USD ($)	Jul. 31, 2018	Sep. 30, 2018	Sep. 30, 2017	Jun. 30, 2018	Dec. 23, 2016
Debt Instrument [Line Items]
Aggregate principal amount of loan		$ 260,100,000		$ 10,000,000
Long term debt, net		258,000,000		$ 9,300,000
Principal repayment		40,000,000	$ 25,000,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Principal repayment		$ 40,000,000
Revolving Credit Facility [Member] | Amendment to Credit Agreement [Member]
Debt Instrument [Line Items]
Aggregate principal amount of loan	$ 300,000,000
Upfront fees	1,800,000
Debt issuance costs	300,000
Long term debt, net	297,900,000
Scheduled principal payments prior to maturity date	$ 0
Revolving Credit Facility [Member] | Counsyl Inc [Member] | Amendment to Credit Agreement [Member]
Debt Instrument [Line Items]
Loan agreement, maturity date	Jul. 31, 2023
Loans maximum borrowing capacity	$ 350,000,000				$ 300,000,000

Long-Term Debt - Schedule of Lo

Long-Term Debt - Schedule of Long-Term Debt (Detail) - USD ($) $ in Millions	Sep. 30, 2018	Jun. 30, 2018
Long-term Debt, Unclassified [Abstract]
Long-term debt	$ 260.1	$ 10
Long-term debt discount	(2.1)	(0.7)
Net long-term debt	$ 258	$ 9.3

Other Long Term Liabilities - S

Other Long Term Liabilities - Summary of Other Long Term Liabilities (Detail) - USD ($) $ in Millions	Sep. 30, 2018	Jun. 30, 2018
Other Liabilities Disclosure [Abstract]
Pension obligation	$ 6.1	$ 6
Other	0.2	0.3
Total other long term liabilities	$ 6.3	$ 6.3

Other Long Term Liabilities - A

Other Long Term Liabilities - Additional Information (Detail) $ in Millions	Sep. 30, 2018USD ($)plan	Jun. 30, 2018USD ($)
Other Liabilities Disclosure [Abstract]
Number of defined benefit pension plans | plan	2
Fair value of plan assets	$ 0.1
Net pension liability	$ 6.1	$ 6

Preferred and Common Stockhol_3

Preferred and Common Stockholder's Equity - Additional Information (Detail) - USD ($)	Sep. 30, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2016
Class of Stock [Line Items]
Preferred stock, shares authorized	5,000,000
Preferred stock, par value	$ 0.01
Preferred stock, shares outstanding	0
Common stock, shares authorized	150,000,000
Common stock, par value	$ 0.01
Common stock, shares issued	74,700,000	70,600,000	68,400,000
Common stock, shares outstanding	74,700,000	70,600,000	68,400,000
Share repurchase program, remaining authorized repurchase amount	$ 160,700,000
Eighth Share Repurchase Program [Member]
Class of Stock [Line Items]
Share repurchase program, authorized amount				$ 200,000,000

Preferred and Common Stockhol_4

Preferred and Common Stockholder's Equity - Summary of Common Shares Issued and Outstanding (Detail) - shares shares in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2018	Jun. 30, 2018
Equity [Abstract]
Common stock issued, Beginning balance	70.6	68.4
Common stock outstanding, Beginning balance	70.6	68.4
Common stock issued upon exercise of options and employee stock plans	4.1	2.2
Common stock issued, Ending balance	74.7	70.6
Common stock outstanding, Ending balance	74.7	70.6

Preferred and Common Stockhol_5

Preferred and Common Stockholder's Equity - Reconciliation of Denominators of Basic and Diluted Earnings Per Share Computations (Detail) - shares shares in Millions	3 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Equity [Abstract]
Weighted-average shares outstanding used to compute basic EPS	73	68.6
Effect of dilutive shares		1.8
Weighted-average shares outstanding and dilutive securities used to compute diluted EPS	73	70.4

Preferred and Common Stockhol_6

Preferred and Common Stockholder's Equity - Schedule of Anti-Dilutive Options and Restricted Stock Units Excluded from EPS Computation (Detail) - shares shares in Millions	3 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Equity [Abstract]
Anti-dilutive options and RSU's excluded from EPS computation	4.1	1.5

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended			6 Months Ended		12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2019	Jun. 30, 2018
Income Tax Contingency [Line Items]
U.S. federal statutory rate	21.00%			21.00%	35.00%		28.00%
Tax Act, incomplete accounting, provisional adjustments		$ (32,600,000)
Earnings per share increase		$ 0.45
Tax Act, limitation on deduction of executive compensation	$ 1,000,000
Tax Act, incomplete accounting, transition tax for accumulated foreign earnings, provisional income tax expense	0
Income tax expense	$ 1,600,000		$ 4,500,000
Approximate rate on pre-tax income	200.00%		5.40%
Scenario, Plan [Member]
Income Tax Contingency [Line Items]
U.S. federal statutory rate						21.00%
Foreign Tax Authority [Member]
Income Tax Contingency [Line Items]
Tax Act, incomplete accounting, provisional adjustments	$ 0
Foreign Tax Authority [Member] | Earliest Tax Year [Member] | Federal Ministry of Finance, Germany [Member]
Income Tax Contingency [Line Items]
Tax year being audited in income tax examination	2,013
Foreign Tax Authority [Member] | Latest Tax Year [Member] | Federal Ministry of Finance, Germany [Member]
Income Tax Contingency [Line Items]
Tax year being audited in income tax examination	2,015
State Tax Authority [Member] | Earliest Tax Year [Member] | State of New Jersey [Member]
Income Tax Contingency [Line Items]
Tax year being audited in income tax examination	2,013
State Tax Authority [Member] | Latest Tax Year [Member] | State of New Jersey [Member]
Income Tax Contingency [Line Items]
Tax year being audited in income tax examination	2,017

Share-Based Compensation - Addi

Share-Based Compensation - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended	3 Months Ended
	Sep. 30, 2014	Sep. 30, 2018	Nov. 30, 2017	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, description		Options and restricted stock units granted to our non-employee directors vest in full upon completion of one year of service on the Board following the date of the grant.
Total unrecognized share-based compensation cost related to stock options		$ 0
Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period of share-based compensation vested, years		4 years
Stock options [Member] | Share-based compensation granted after December 5, 2012 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expire from date of grant, years		8 years
Stock options [Member] | Share-based compensation granted prior to December 5, 2012 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expire from date of grant, years		10 years
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period of share-based compensation vested, years	4 years
Total unrecognized share-based compensation cost related to RSUs		$ 69.8
Total unrecognized share-based compensation cost, weighted-average period, years		2 years 8 months 12 days
Restricted Stock Units (RSUs) [Member] | Non Employee Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period of share-based compensation vested, years		1 year
The 2017 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares approved			1,400,000
Common stock shares available for issuance		400,000
The 2017 Plan [Member] | Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grant		600,000
The 2010 Plan [Member] | Options and Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grant		5,700,000
2012 Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares approved				2,000,000
Shares issued under the Plan		700,000

Share-Based Compensation - Sche

Share-Based Compensation - Schedule of Share-Based Compensation Arrangement by Share Based Payment Award Options Outstanding (Detail) shares in Millions	3 Months Ended
	Sep. 30, 2018$ / sharesshares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Options outstanding at beginning of period, Number of shares | shares	6.3
Options granted, Number of shares | shares	0
Options exercised, Number of shares | shares	(0.6)
Options canceled or expired, Number of shares | shares	0
Options outstanding at end of year, Number of shares | shares	5.7
Options exercisable at end of period, Number of shares | shares	5.7
Options outstanding at beginning of period, Weighted average exercise price | $ / shares	$ 24.50
Options granted, Weighted average exercise price | $ / shares	0
Options exercised, Weighted average exercise price | $ / shares	23.84
Options canceled or expired, Weighted average exercise price | $ / shares	0
Options outstanding at end of year, Weighted average exercise price | $ / shares	24.57
Options exercisable at end of period, Weighted average exercise price | $ / shares	$ 24.57

Share-Based Compensation - Sc_2

Share-Based Compensation - Schedule of Share-Based Compensation Arrangement by Share Based Payment Award Restricted Stock Units Outstanding (Detail) - Restricted Stock Units (RSUs) [Member] shares in Millions	3 Months Ended
	Sep. 30, 2018$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSUs outstanding at beginning of period, Number of shares | shares	2.2
RSUs granted, Number of shares | shares	1.1
RSUs vested, Number of shares | shares	(0.8)
RSUs canceled, Number of shares | shares	0
RSUs outstanding at end of period, Number of shares | shares	2.5
RSUs outstanding at beginning of period, Weighted average grant date fair value | $ / shares	$ 31.12
RSUs granted, Weighted average grant date fair value | $ / shares	47.81
RSUs vested, Weighted average grant date fair value | $ / shares	32.39
RSUs canceled, Weighted average grant date fair value | $ / shares	0
RSUs outstanding at end of period, Weighted average grant date fair value | $ / shares	$ 38.06

Share-Based Compensation - Sc_3

Share-Based Compensation - Schedule of Share-Based Compensation Recognized in Consolidated Statements of Operations (Detail) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense	$ 7.7	$ 6.4
Molecular Diagnostic Testing Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense	0.2	0.2
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
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	0.8
Selling, General, and Administrative Expenses [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense	$ 6.2	$ 5.3

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) $ in Millions	Sep. 30, 2018USD ($)
Level 3 [Member]
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items]
Estimated fair value of long-term debt	$ 209.3

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Fair Value of Financial Assets and Liabilities (Detail) - USD ($) $ in Millions		Sep. 30, 2018	Jun. 30, 2018
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items]
Total fair value of financial assets and liability		$ 93	$ 101.2
Money Market Funds [Member]
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items]
Total fair value of financial assets	[1]	6.1	12.5
Corporate Bonds and Notes [Member]
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items]
Total fair value of financial assets		60.7	53.3
Municipal Bonds [Member]
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items]
Total fair value of financial assets		23.4	29.2
Federal Agency Issues [Member]
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items]
Total fair value of financial assets		9.5	12.4
US Government Securities [Member]
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items]
Total fair value of financial assets		8.2	8.3
Contingent Consideration [Member]
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items]
Total fair value of financial liability		(14.9)	(14.5)
Level 1 [Member]
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items]
Total fair value of financial assets and liability		9.5	15.3
Level 1 [Member] | Money Market Funds [Member]
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items]
Total fair value of financial assets	[1]	6.1	12.5
Level 1 [Member] | Corporate Bonds and Notes [Member]
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items]
Total fair value of financial assets		3.4	2.8
Level 2 [Member]
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items]
Total fair value of financial assets and liability		98.4	100.4
Level 2 [Member] | Corporate Bonds and Notes [Member]
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items]
Total fair value of financial assets		57.3	50.5
Level 2 [Member] | Municipal Bonds [Member]
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items]
Total fair value of financial assets		23.4	29.2
Level 2 [Member] | Federal Agency Issues [Member]
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items]
Total fair value of financial assets		9.5	12.4
Level 2 [Member] | US Government Securities [Member]
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items]
Total fair value of financial assets		8.2	8.3
Level 3 [Member]
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items]
Total fair value of financial assets and liability		(14.9)	(14.5)
Level 3 [Member] | Contingent Consideration [Member]
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items]
Total fair value of financial liability		$ (14.9)	$ (14.5)
[1]	Money market funds are primarily comprised of exchange traded funds and accrued interest

Fair Value Measurements - Chang

Fair Value Measurements - Change in Fair Value of Contingent Consideration (Detail) $ in Millions	3 Months Ended
	Sep. 30, 2018USD ($)
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Abstract]
Balance June 30, 2018	$ 14.5
Change in fair value recognized in the income statement	0.4
Ending balance September 30, 2018	$ 14.9

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	3 Months Ended
	Sep. 30, 2018USD ($)
Commitments And Contingencies Disclosure [Abstract]
Claims made against the company	$ 0

Employee Deferred Savings Pla_2

Employee Deferred Savings Plan - Additional Information (Detail)	3 Months Ended
	Sep. 30, 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%

Employee Deferred Savings Pla_3

Employee Deferred Savings Plan - Company Recorded Contributions To Plan (Detail) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Compensation And Retirement Disclosure [Abstract]
Deferred savings plan contributions	$ 2	$ 1.9

Segment and Related Informati_3

Segment and Related Information - Additional Information (Detail)	3 Months Ended
	Sep. 30, 2018Segment
Segment Reporting [Abstract]
Number of reportable segment	2

Segment and Related Informati_4

Segment and Related Information - Schedule of Segment Performance Based on Income (Loss) before Interest Income and Other Income and Expense (Detail) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
Revenues	$ 202.3	$ 178.8
Depreciation and amortization	18.3	13.2
Segment operating income (loss)	1.2	84
Diagnostics [Member]
Segment Reporting Information [Line Items]
Revenues	189	167.4
Depreciation and amortization	17	11.8
Segment operating income (loss)	27.6	30.6
Other [Member]
Segment Reporting Information [Line Items]
Revenues	13.3	11.4
Depreciation and amortization	1.3	1.4
Segment operating income (loss)	$ (26.4)	$ 53.4

Segment and Related Informati_5

Segment and Related Information - Schedule of Total Operating Income for Reportable Segments (Detail) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting [Abstract]
Total operating income for reportable segments	$ 1.2	$ 84
Interest income	0.7	0.4
Interest expense	(2.2)	(0.9)
Other	1.1	(0.3)
Income before income tax	0.8	83.2
Income tax provision	1.6	4.5
Net income (loss)	(0.8)	78.7
Net loss attributable to non-controlling interest	(0.1)	(0.1)
Net income (loss) attributable to Myriad Genetics, Inc. stockholders	$ (0.7)	$ 78.8

Supplemental Cash Flow Inform_3

Supplemental Cash Flow Information - Schedule of Supplemental Cash Flow Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Supplemental Cash Flow Elements [Abstract]
Cash paid during the period for income taxes	$ 4.9	$ 5.2
Cash paid for interest	$ (0.9)	$ (1)