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Period Type:	instant

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from financing costs.

No definition available.

Name:	epix_DeferredTaxAssetsFinancingCosts
Namespace Prefix:	epix_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-2

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Period Type:	instant

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from investments (excludes investments in subsidiaries and equity method investments).

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-6

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Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-2

Name:	us-gaap_DeferredTaxAssetsNet
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- References

No definition available.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards.

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Period Type:	instant

Amount, before allocation of valuation allowance, of deferred tax asset attributable to deductible temporary differences, classified as other.

Name:	us-gaap_DeferredTaxAssetsOther
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Data Type:	xbrli:monetaryItemType
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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible research tax credit carryforwards.

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

Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-2