Condensed Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Cash Flows from Operating Activities:
Net loss	$ (843)us-gaap_NetIncomeLoss	$ (677)us-gaap_NetIncomeLoss
Adjustments to reconcile net loss to net cash flows provided by operating activities:
Depreciation	876us-gaap_Depreciation	900us-gaap_Depreciation
Amortization of deferred grant income	(235)pwx_AmortizationOfDeferredGrantsIncome	(140)pwx_AmortizationOfDeferredGrantsIncome
Deferred grant and other income	288pwx_DeferredGrantIncomeAndOther	195pwx_DeferredGrantIncomeAndOther
Deferred income taxes benefit	(447)us-gaap_DeferredIncomeTaxExpenseBenefit	(641)us-gaap_DeferredIncomeTaxExpenseBenefit
Share-based compensation	98us-gaap_ShareBasedCompensation	114us-gaap_ShareBasedCompensation
Increase (decrease) in cash from:
Accounts receivable	278	1,325
Materials and supplies	10us-gaap_IncreaseDecreaseInInventories	39us-gaap_IncreaseDecreaseInInventories
Prepaid expenses and other	340	249
Accounts payable and accrued expenses	444	(689)
Net cash flows provided by operating activities	809	675
Cash flows from Investing Activities:
Purchase of property and equipment	(350)	(275)
Net cash flows used in investing activities	(350)	(275)
Cash Flows from Financing Activities:
Dividends paid	(198)us-gaap_PaymentsOfOrdinaryDividends	(197)us-gaap_PaymentsOfOrdinaryDividends
Issuance of common shares for stock options exercised and employee stock purchases	12	31
Net cash flows used in financing activities	(186)	(166)
Increase in Cash and Cash Equivalents	273	234
Cash and Cash Equivalents, Beginning of Period	6,414	2,614
Cash and Cash Equivalents, End of Period	6,687	2,848
Supplemental Disclosures:
Property and equipment included in accounts payable	217	61
Cash paid for income taxes	$ 385us-gaap_IncomeTaxesPaid	$ 55us-gaap_IncomeTaxesPaid

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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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Amount of cash inflow (outflow) of financing activities, excluding discontinued operations. Financing activity cash flows include obtaining resources from owners and providing them with a return on, and a return of, their investment; borrowing money and repaying amounts borrowed, or settling the obligation; and obtaining and paying for other resources obtained from creditors on long-term credit.

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Amount of cash inflow (outflow) of investing activities, excluding discontinued operations. Investing activity cash flows include making and collecting loans and acquiring and disposing of debt or equity instruments and property, plant, and equipment and other productive assets.

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Amount of cash inflow (outflow) from operating activities, excluding discontinued operations. Operating activity cash flows include transactions, adjustments, and changes in value not defined as investing or financing activities.

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The cash outflow associated with the acquisition of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale; includes cash outflows to pay for construction of self-constructed assets.

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The total cash inflow associated with the amount received from holders to acquire the entity's shares under incentive and share awards, including stock option exercises. This item inherently excludes any excess tax benefit, which the entity may have realized and reported separately.

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