Document and Entity Information	0 Months Ended
Dec. 31, 2014
Risk/Return:
Document Type	485BPOS
Document Period End Date	Dec. 31, 2014
Registrant Name	DREYFUS US TREASURY LONG TERM FUND
Central Index Key	0000779129
Amendment Flag	false
Document Creation Date	Apr. 27, 2015
Document Effective Date	May 01, 2015
Prospectus Date	May 01, 2015
DREYFUS ONE HUNDRED PERCENT US TREASURY MONEY MARKET FUND \| DREYFUS ONE HUNDRED PERCENT US TREASURY MONEY MARKET FUND
Risk/Return:
Trading Symbol	DUSXX
DREYFUS US TREASURY INTERMEDIATE TERM FUND \| DREYFUS US TREASURY INTERMEDIATE TERM FUND
Risk/Return:
Trading Symbol	DRGIX
DREYFUS US TREASURY LONG TERM FUND \| DREYFUS US TREASURY LONG TERM FUND
Risk/Return:
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 date when a document, upon receipt and acceptance, becomes officially effective, in CCYY-MM-DD format. Usually it is a system-assigned date time value, but it may be declared by the submitter in some cases.

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The end date of the period reflected on the cover page if a periodic report. For all other reports and registration statements containing historical data, it is the date up through which that historical data is presented. If there is no historical data in the report, use the filing date. The format of the date is CCYY-MM-DD.

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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.

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

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The exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC.

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- Definition

The date of the prospectus.

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