Deferred revenue related party.

No definition available.

Name:	fmi_DeferredRevenueRelatedParty
Namespace Prefix:	fmi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130549-203045

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(3))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_AccountsReceivableNetCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_AssetsAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The carrying amount of consideration received or receivable as of the balance sheet date on potential earnings that were not recognized as revenue in conformity with GAAP, and which are expected to be recognized as such within one year or the normal operating cycle, if longer, including sales, license fees, and royalties, but excluding interest income.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 8
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82887183&loc=d3e6935-107765

+ Details

Name:	us-gaap_DeferredRevenueCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_LiabilitiesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of noncurrent assets classified as other.

+ References

+ Details

Name:	us-gaap_OtherAssetsNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of asset related to consideration paid in advance for costs that provide economic benefits in future periods, and amount of other assets that are expected to be realized or consumed within one year or the normal operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(7))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82887183&loc=d3e6676-107765

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(8))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_PrepaidExpenseAndOtherAssetsCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The cumulative amount of the reporting entity's undistributed earnings or deficit.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(30)(a)(3))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(23)(a)(4))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

+ Details

Name:	us-gaap_RetainedEarningsAccumulatedDeficit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130543-203045

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130539-203045

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130545-203045

+ Details

Name:	us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of revenue, fees and commissions earned from transactions between (a) a parent company and its subsidiaries; (b) subsidiaries of a common parent; (c) an entity and trusts for the benefit of employees, for example, but not limited to, pension and profit-sharing trusts that are managed by or under the trusteeship of the entity's management; (d) an entity and its principal, owners, management, or members of their immediate families; and (e) affiliates.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07.1(c))
-URI http://asc.fasb.org/extlink&oid=114873854&loc=SL114874292-224272

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1(e))
-URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227

+ Details

Name:	us-gaap_RevenueFromRelatedParties
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- References

No definition available.

+ Details

Name:	us-gaap_StockholdersEquityAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	srt_ProductOrServiceAxis=fmi_MolecularInformationServicesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=fmi_PharmaResearchAndDevelopmentServicesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=fmi_RocheMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=us-gaap_AccountingStandardsUpdate201409Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InitialApplicationPeriodCumulativeEffectTransitionAxis=us-gaap_DifferenceBetweenRevenueGuidanceInEffectBeforeAndAfterTopic606Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InitialApplicationPeriodCumulativeEffectTransitionAxis=us-gaap_CalculatedUnderRevenueGuidanceInEffectBeforeTopic606Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Summary of Significant Accounting Policies - Schedule of Impact of Adoption on Condensed Consolidated Statement of Operations and Condensed Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jan. 01, 2018	Dec. 31, 2017
Assets
Accounts receivable	$ 40,939		$ 40,939			$ 19,967
Prepaid expenses and other current assets	5,641		5,641			9,118
Other assets	3,142		3,142			1,760
Liabilities:
Deferred revenue	10,720		10,720			2,212
Roche related-party deferred revenue	8,190		8,190			3,742
Stockholders’ equity:
Accumulated deficit	(558,851)		(558,851)			$ (506,349)
Molecular Information Services [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Revenue	38,702	$ 24,777	70,478	$ 40,371
Pharma Research and Development Services [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Revenue	3,732	1,215	8,514	2,302
Roche [Member] \| Molecular Information Services [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Related-party revenue	12,005	5,520	26,820	11,024
Roche [Member] \| Pharma Research and Development Services [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Related-party revenue	2,567	$ 3,492	4,034	$ 7,635
ASU 2014-09 [Member]
Assets
Accounts receivable					$ 37,210
Prepaid expenses and other current assets					9,828
Other assets					2,333
Liabilities:
Deferred revenue					2,368
Roche related-party deferred revenue					3,820
Stockholders’ equity:
Accumulated deficit					(488,057)
Effect of Change Higher/(Lower) \| ASU 2014-09 [Member]
Assets
Accounts receivable	(12,077)		(12,077)		17,243
Prepaid expenses and other current assets	(177)		(177)		710
Other assets	(357)		(357)		573
Liabilities:
Deferred revenue	(136)		(136)		156
Roche related-party deferred revenue	(1,259)		(1,259)		78
Stockholders’ equity:
Accumulated deficit	(11,216)		(11,216)		$ 18,292
Effect of Change Higher/(Lower) \| ASU 2014-09 [Member] \| Molecular Information Services [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Revenue	1,890		5,102
Effect of Change Higher/(Lower) \| ASU 2014-09 [Member] \| Pharma Research and Development Services [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Revenue	4,050		128
Effect of Change Higher/(Lower) \| ASU 2014-09 [Member] \| Roche [Member] \| Molecular Information Services [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Related-party revenue	1,995		1,620
Balances Without Adoption of ASC 606 \| ASU 2014-09 [Member]
Assets
Accounts receivable	28,862		28,862
Prepaid expenses and other current assets	5,464		5,464
Other assets	2,785		2,785
Liabilities:
Deferred revenue	10,584		10,584
Roche related-party deferred revenue	6,931		6,931
Stockholders’ equity:
Accumulated deficit	(570,067)		(570,067)
Balances Without Adoption of ASC 606 \| ASU 2014-09 [Member] \| Molecular Information Services [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Revenue	40,592		75,580
Balances Without Adoption of ASC 606 \| ASU 2014-09 [Member] \| Pharma Research and Development Services [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Revenue	7,782		8,642
Balances Without Adoption of ASC 606 \| ASU 2014-09 [Member] \| Roche [Member] \| Molecular Information Services [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Related-party revenue	14,000		28,440
Balances Without Adoption of ASC 606 \| ASU 2014-09 [Member] \| Roche [Member] \| Pharma Research and Development Services [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Related-party revenue	$ 2,567		$ 4,034