Represents the Business combination cash consideration per share.

No definition available.

Name:	ecyt_BusinessCombinationCashConsiderationPerShare
Namespace Prefix:	ecyt_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the maximum reimbursement amount of out-of-pocket fees and expenses under business combination.

+ References

No definition available.

+ Details

Name:	ecyt_BusinessCombinationOutOfPocketFeesAndExpensesMaximumReimbursementAmount
Namespace Prefix:	ecyt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the reverse termination fee under business combination.

+ References

No definition available.

+ Details

Name:	ecyt_BusinessCombinationReverseTerminationFee
Namespace Prefix:	ecyt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the termination fee payable under business combination.

+ References

No definition available.

+ Details

Name:	ecyt_BusinessCombinationTerminationFee
Namespace Prefix:	ecyt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Face amount or stated value per share of common stock.

+ 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(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_CommonStockParOrStatedValuePerShare
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=ecyt_MergerAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

Subsequent Event (Details) - USD ($) $ / shares in Units, $ in Millions	Oct. 17, 2018	Sep. 30, 2018	Dec. 31, 2017
Subsequent Event [Line Items]
Common stock, par value (in dollars per share)		$ 0.001	$ 0.001
Subsequent Event \| Merger agreement \| Novartis
Subsequent Event [Line Items]
Common stock, par value (in dollars per share)	$ 0.001
Cash consideration per share (in dollars per share)	$ 24.00
Termination fee	$ 73.5
Reverse termination fee	150.0
Subsequent Event \| Merger agreement \| Novartis \| Maximum
Subsequent Event [Line Items]
Out-of-pocket fees and expenses maximum reimbursement amount	$ 5.0