Document and Entity Information	6 Months Ended
	Jun. 30, 2012	Aug. 01, 2012
Document and Entity Information [Abstract]
Entity Registrant Name	PROVIDENCE & WORCESTER RAILROAD CO/RI/
Entity Central Index Key	0000831968
Document Type	10-Q/A
Document Period End Date	Jun. 30, 2012
Amendment Flag	true
Amendment Description	This Amendment No. 1 on Form 10-Q/A (“Form 10-Q/A”) amends and restates the Quarterly Report on Form 10-Q of Providence and Worcester Railroad Company (the “Company”) for the quarter ended June 30, 2012, as originally filed with the Securities and Exchange Commission (the “SEC”) on August 13, 2012 (the “Original Filing”). This Form 10-Q/A is being filed to restate the Company’s financial statements in Item 1 and related disclosures (including certain amounts and disclosures in Management’s Discussion and Analysis of Financial Condition and Results of Operations in Item 2) for the three and six-month periods ended June 30, 2012, as discussed in Note 13 to the financial statements included in Item 1. The Company’s financial statements included in the Original Filing reflected $3.2 million of other income from settlement of the Amtrak Agreement for the quarter ended June 30, 2012. The Company’s financial statements included in the Original Filing also reflected $3.2 million of other income from the settlement of the Amtrak Agreement for the six-month periods ended June 30, 2012. The Company has determined that the Amtrak Agreement should have been presented as a reduction of operating expenses. Additionally, the Company reduced related accounts receivable and deferred revenue recorded in conjunction with the Amtrak Agreement in the amount of $2.4 million. The Company also increased property and equipment $684 thousand as a result of the Amtrak Agreement. As a result, in this Form 10-Q/A, the Company is restating its financial statements and related disclosures to recognize a reduction of both other income and operating expenses for the three and six-month periods ended June 30, 2012 for this item and its balance sheet at June 30, 2012. Such adjustments have no impact on operating income, net income or net cash flows.In connection with this restatement, the Company also chose to correct classification errors within other income that were immaterial individually and in the aggregate. These classification changes moved income previously included within revenues to other income below operating income for the three and six months ended June 30, 2012 and 2011. Such amounts were $23 thousand and $97 thousand for the three months ended June 30, 2012 and 2011, respectively and $26 thousand and $126 thousand for the six months ended June 30, 2012 and 2011, respectively. Although this Form 10-Q/A supersedes the Original Filing in its entirety, this Form 10-Q/A only amends and restates Items 1 and 2 solely as a result of, and to reflect the restatement and classification adjustments referred to above, and no other information in the Original Filing is amended hereby. While the foregoing items have been updated, this amended report does not reflect any other events occurring after the Original Filing. In addition, currently-dated certifications from our Chief Executive Officer and Chief Financial Officer, as required by Sections 302 and 906 of the Sarbanes-Oxley Act of 2002, are attached to this Form 10-Q/A as Exhibits 31.1, 31.2, 32.1 and 32.2, respectively.
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--12-31
Entity Filer Category	Smaller Reporting Company
Entity Common Stock, Shares Outstanding		4,837,973