Document and Entity Information	Total
Prospectus:
Document Type	485BPOS
Document Period End Date	Dec. 31, 2016
Registrant Name	DREYFUS US TREASURY LONG TERM FUND
Central Index Key	0000779129
Amendment Flag	false
Document Creation Date	Apr. 27, 2017
Document Effective Date	May 01, 2017
Prospectus Date	May 01, 2017
Dreyfus U.S. Treasury Intermediate Term Fund \| DREYFUS US TREASURY INTERMEDIATE TERM FUND
Prospectus:
Trading Symbol	DRGIX
Dreyfus U.S. Treasury Long Term Fund \| DREYFUS US TREASURY LONG TERM FUND
Prospectus:
Trading Symbol	DRGBX

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The date the document was made available and submitted, in CCYY-MM-DD format. The date of submission, date of acceptance by the recipient, and the document effective date are all potentially different.

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The type of document being provided (such as 10-K, 10-Q, 485BPOS, etc). The document type is limited to the same value as the supporting SEC submission type, or the word "Other".

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A unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. It is commonly abbreviated as CIK.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation 12B
-Number 240
-Section 12b
-Subsection 1

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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The date of the prospectus.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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