Investments unrealized gains (Details) - USD ($)	3 Months Ended	12 Months Ended
Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Unrealized gain on securities	$ 1,756		$ 0
Unrealized loss on securities	80,899		64,433
Realized gain on securities	0	$ 0
Realized loss on securities	$ 0		$ 0

Amount of realized gain on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

No definition available.

+ Details

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Period Type:	duration

- Definition

Amount of realized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

No definition available.

+ Details

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Namespace Prefix:	ecyt_
Data Type:	xbrli:monetaryItemType
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Period Type:	duration

- Definition

Amount of unrealized gain before deducting unrealized loss on investments in debt securities classified as available-for-sale securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563

+ Details

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Data Type:	xbrli:monetaryItemType
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Period Type:	duration

- Definition

Amount of unrealized loss before deducting unrealized gain on investments in available-for-sale debt securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563

+ Details

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

- References

No definition available.

+ Details

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