The amount received during the period for the achievement of milestone.

No definition available.

Name:	armp_AmountReceivedUponAchievementOfMilestone
Namespace Prefix:	armp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the period for which the company ceases to use commercially reasonable efforts directed to the development of the product.

+ References

No definition available.

+ Details

Name:	armp_AwardAgreementInterruptionPeriod
Namespace Prefix:	armp_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents about award line items.

+ References

No definition available.

+ Details

Name:	armp_AwardLineItems
Namespace Prefix:	armp_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The carrying amount as of the balance sheet date of award receivable.

+ References

No definition available.

+ Details

Name:	armp_AwardReceivable
Namespace Prefix:	armp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Research and development credits recognized.

+ References

No definition available.

+ Details

Name:	armp_ResearchAndDevelopmentCreditsRecognized
Namespace Prefix:	armp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The threshold amount of development award under the award agreement.

+ References

No definition available.

+ Details

Name:	armp_ThresholdDevelopmentAward
Namespace Prefix:	armp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of revenue that is not accounted for under Topic 606.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(1))
-URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227

+ Details

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

- Details

Name:	srt_CounterpartyNameAxis=armp_MedicalTechnologyEnterpriseConsortiumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=armp_CysticFibrosisFoundationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Grants and Awards (Narrative) (Details) - USD ($)			3 Months Ended		6 Months Ended
Grants and Awards (Narrative) (Details) - USD ($)	Jul. 15, 2020	Mar. 13, 2020	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Award [Line Items]
Revenue from grants			$ 1,168,000	$ 31,000	$ 2,234,000	$ 31,000
Award receivable			1,168,000		1,168,000		$ 561,000
Medical Technology Enterprise Consortium [Member]
Award [Line Items]
Revenue from grants	$ 15,000,000.0
Cystic Fibrosis Foundation [Member]
Award [Line Items]
Award receivable		$ 1,000,000.0
Additional amount received			800,000
Award agreement interruption period		360 days
Research and development credits recognized			$ 800,000	$ 900,000	$ 800,000	$ 1,000,000.0
Maximum [Member] \| Cystic Fibrosis Foundation [Member]
Award [Line Items]
Amount of threshold development award		$ 5,000,000.0