Westport Fuel Systems (WPRT) 40-F 9 Mar 15 2014 FY Annual report (Canada) Financial data

Document_And_Entity_Informatio

Document And Entity Information	12 Months Ended
	Dec. 31, 2014
Document Information [Line Items]
Entity Registrant Name	WESTPORT INNOVATIONS INC
Entity Central Index Key	1370416
Document Type	40-F
Document Period End Date	31-Dec-14
Amendment Flag	FALSE
Current Fiscal Year End Date	-19
Entity Current Reporting Status	Yes
Entity Common Stock, Shares Outstanding	63,480,722
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets:
Cash and cash equivalents	$93,282	$178,513
Short-term investments	723	32,091
Accounts receivable (note 5)	46,849	59,315
Inventories (note 6)	41,824	40,626
Prepaid expenses	4,641	6,072
Current portion of deferred income tax assets (note 19(b))	3,556	3,109
Total current assets	190,875	319,726
Long-term investments (note 7)	33,324	22,128
Other assets	3,819	2,245
Property, plant and equipment (note 9)	58,134	67,349
Intangible assets (note 10)	27,920	38,344
Deferred income tax assets (note 19(b))	271	379
Goodwill (note 11)	23,352	41,500
Total assets	337,695	491,671
Current liabilities:
Accounts payable and accrued liabilities (note 12)	55,502	54,792
Current portion of deferred revenue	1,782	6,727
Current portion of deferred income tax liabilities (note 19(b))	398	468
Current portion of long-term debt (note 13)	18,955	53,025
Current portion of warranty liability (note 14)	9,696	9,955
Total current liabilities	86,333	124,967
Warranty liability (note 14)	13,413	18,890
Long-term debt (note 13)	59,587	12,988
Deferred revenue	3,795	4,580
Deferred income tax liabilities (note 19(b))	4,954	4,903
Other long-term liabilities (note 15)	1,605	2,441
Total liabilities	169,687	168,769
Share capital (note 17):
Authorized: Unlimited common shares, no par value Unlimited preferred shares in series, no par value Issued: 63,480,722 (2013 - 62,733,762) common shares	930,857	916,497
Other equity instruments	7,767	13,834
Additional paid in capital	9,837	8,205
Accumulated deficit	-764,960	-615,342
Accumulated other comprehensive income	-15,493	-292
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	168,008	322,902
Commitments and contingencies (note 22)
Total liabilities and shareholders' equity	$337,695	$491,671

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets [Parenthetical] (USD $)	Dec. 31, 2014	Dec. 31, 2013
Common Stock, No Par Value	$0	$0
Preferred Stock, No Par Value	$0	$0
Common shares, shares issued (in shares)	63,480,722	62,733,762

Consolidated_Statements_of_Ope

Consolidated Statements of Operations and Comprehensive Income (Loss) (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Product revenue	$118,015	$148,001	$132,382
Service and other revenue (note 21)	12,554	16,031	23,244
Revenue, Net	130,569	164,032	155,626
Cost of revenue and expenses:
Cost of product revenue	97,923	148,690	102,486
Research and development (note 17(d) and 18)	76,580	91,132	73,198
General and administrative (note 17(d))	40,319	46,475	44,811
Sales and marketing (note 17(d))	25,489	28,707	30,112
Foreign exchange (gain) loss	-3,434	-15,168	1,185
Depreciation and amortization (note 9 and 10)	18,666	16,288	11,395
Bank charges, interest and other	703	595	737
Impairment of long lived assets	5,238	4,838	0
Provision for inventory purchase commitments (note 12 and 22(b))	4,106	0	0
Intangible impairment (note 10)	5,823	1,721	0
Goodwill impairment (note 11)	18,543	34,964	0
Cost of Revenue	289,956	358,242	263,924
Loss from operations	-159,387	-194,210	-108,298
Income from investments accounted for by the equity method	14,222	13,444	16,190
Interest on long-term debt and amortization of discount	-5,849	-4,789	-5,354
Interest and other income	817	1,018	426
Loss before income taxes	-150,197	-184,537	-97,036
Income tax expense (recovery) (note 19):
Current	606	1,414	2,147
Deferred	-1,185	-541	-409
Income Tax Expense (Benefit)	-579	873	1,738
Net loss for the year	-149,618	-185,410	-98,774
Other comprehensive income (loss):
Cumulative translation adjustment	-15,201	-17,308	3,745
Comprehensive loss	($164,819)	($202,718)	($95,029)
Loss per share:
Basic and diluted (in dollars per share)	($2.37)	($3.22)	($1.83)
Weighted average common shares outstanding:
Basic and diluted (in shares)	63,130,022	57,633,190	54,072,513

Consolidated_Statements_of_Sha

Consolidated Statements of Shareholders' Equity (USD $)	Total	Share capital [Member]	Other equity instruments [Member]	Additional paid in capital [Member]	Accumulated deficit [Member]	Accumulated other comprehensive income [Member]
In Thousands, except Share data
Balance at Dec. 31, 2011	$152,590	$459,866	$6,112	$4,499	($331,158)	$13,271
Balance (in shares) at Dec. 31, 2011		48,455,601
Issue of common shares on exercise of stock options	969	1,492	0	-523	0	0
Issue of common shares on exercise of stock options (in shares)		93,044
Issue of common shares on exercise of share units	0	6,597	-6,597	0	0	0
Issue of common shares on exercise of share units (in shares)		420,446
Issue of common shares on public offering	273,556	273,556	0	0	0	0
Issue of common shares on public offering (in shares)		6,325,000
Share issue costs	-8,126	-8,126	0	0	0	0
Stock-based compensation	12,121	0	9,713	2,408	0	0
Net loss for the year	-98,774	0	0	0	-98,774	0
Other comprehensive loss	3,745	0	0	0	0	3,745
Balance at Dec. 31, 2012	336,081	733,385	9,228	6,384	-429,932	17,016
Balance (in shares) at Dec. 31, 2012		55,294,091
Issue of common shares on exercise of stock options	741	1,147	0	-406	0	0
Issue of common shares on exercise of stock options (in shares)		111,986
Issue of common shares on exercise of share units	0	10,599	-10,599	0	0	0
Issue of common shares on exercise of share units (in shares)		609,200
Issue of common shares in connection with acquisition	24,091	24,091	0	0	0	0
Issue of common shares in connection with acquisition (in shares)		718,485
Acquisition to be settled by issuance of common shares	3,285	0	3,285	0	0	0
Issue of common shares on public offering	152,340	152,340	0	0	0	0
Issue of common shares on public offering (in shares)		6,000,000
Share issue costs	-5,065	-5,065	0	0	0	0
Stock-based compensation	14,147	0	11,920	2,227	0	0
Net loss for the year	-185,410	0	0	0	-185,410	0
Other comprehensive loss	-17,308	0	0	0	0	-17,308
Balance at Dec. 31, 2013	322,902	916,497	13,834	8,205	-615,342	-292
Balance (in shares) at Dec. 31, 2013		62,733,762
Issue of common shares on exercise of stock options	242	374	0	-132	0	0
Issue of common shares on exercise of stock options (in shares)		43,071
Issue of common shares on exercise of share units	0	10,701	-10,701	0	0	0
Issue of common shares on exercise of share units (in shares)		608,975
Issue of common shares in connection with acquisition	0	3,285	-3,285	0	0	0
Issue of common shares in connection with acquisition (in shares)		94,914
Stock-based compensation	9,683	0	7,919	1,764	0	0
Net loss for the year	-149,618	0	0	0	-149,618	0
Other comprehensive loss	-15,201	0	0	0	0	-15,201
Balance at Dec. 31, 2014	$168,008	$930,857	$7,767	$9,837	($764,960)	($15,493)
Balance (in shares) at Dec. 31, 2014		63,480,722

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash flows from operating activities:
Loss for the period	($149,618)	($185,410)	($98,774)
Items not involving cash:
Depreciation and amortization	18,666	16,288	11,395
Stock-based compensation expense	9,683	14,283	12,468
Unrealized foreign exchange gain	-3,434	-15,168	1,185
Deferred income tax (recovery) expense	-1,185	-541	-409
Income from investments accounted for by the equity method	-14,222	-13,444	-16,190
Amortization of long-term debt	2,139	1,643	2,094
Impairment of long lived assets	5,238	4,838	0
Inventory write-downs to net realizable value	2,102	4,925	0
Provision for inventory purchase commitments (note 12 and 22(b))	4,106	0	0
Intangible impairment	5,823	1,721	0
Goodwill impairment	18,543	34,964	0
Change in fair value of derivative liability and bad debt expense	1,338	-37	340
Changes in non-cash operating working capital:
Accounts receivable	11,629	-12,289	6,733
Inventories	-1,367	5,179	-7,920
Prepaid expenses	-556	513	179
Accounts payable and accrued liabilities	-4,749	-2,064	-742
Deferred revenue	-5,096	5,208	3,115
Warranty liability	-5,797	22,602	1,979
Net cash provided by operating activities	-106,757	-116,789	-84,547
Cash flows from investing activities:
Purchase of property, plant and equipment	-10,249	-26,450	-30,363
Purchase of intangible assets	0	0	-989
Maturity (purchase) of short-term investments, net	31,369	-5,771	-22,520
Repayment of loan receivable	0	0	2,494
Increase loan payable	0	0	2,450
Repayment of loan payable	0	0	-21,840
Acquisitions, net of acquired cash (note 4)	-3,053	1,178	-1,125
Dividends received from joint ventures	3,200	8,287	22,600
Net cash used in investing activities	21,267	-22,756	-49,293
Cash flows from financing activities:
Increase in operating lines of credit	0	0	4,245
Repayment of long term facilities	-9,540	-13,678	-9,843
Issuance of long term debenture notes	17,797	0	0
Finance costs incurred	-2,033	0	0
Proceeds from stock options exercised	242	741	969
Shares issued for cash	0	152,340	273,556
Share issuance costs	0	-5,065	-8,126
Net cash used in financing activities	6,466	134,338	260,801
Effect of foreign exchange on cash and cash equivalents	-6,207	-5,238	-1,288
(Decrease) increase in cash and cash equivalents	-85,231	-10,445	125,673
Cash and cash equivalents, beginning of period	178,513	188,958	63,285
Cash and cash equivalents, end of period	93,282	178,513	188,958
Supplementary information:
Interest paid	4,702	3,911	3,532
Taxes paid, net of refunds	871	1,321	1,982
Non-cash transactions:
Shares issued on exercise of performance share units	10,701	10,599	6,597
Common shares issued in connection with acquisitions (note 4b)	$3,285	$24,091	$0

Company_organization_and_opera

Company organization and operations	12 Months Ended
	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Operations [Text Block]	1	Company organization and operations:
	Westport Innovations Inc. (the “Company”) was incorporated under the Business Corporations Act (Alberta) on March 20, 1995.
	The Company is a provider of high-performance, low-emission engine and fuel system technologies utilizing gaseous fuels. Its technology and products enable light (<5.9 litre), medium (5.9 to 10 litre), heavy-duty (11 to 16 litre) and high horsepower (>16 litre) petroleum-based fuel engines to use primarily natural gas, giving users a cleaner, more plentiful and generally less expensive alternative fuel.
	The Company is focused on developing technology to enable more environmentally sustainable engines without compromising the performance, fuel economy, durability and reliability of diesel engines. The substitution of natural gas for petroleum-based fuel drives a significant reduction in harmful combustion emissions, such as nitrogen oxides, particulate matter and greenhouse gas, in addition to using an abundant, relatively inexpensive alternative fuel. The Company’s systems can be used to enable combustion engines to use gaseous fuels, such as natural gas, propane, renewable natural gas or hydrogen. The Company’s research and development effort and investment have resulted in a substantial patent portfolio that serves as the foundation for its differentiated technology offerings and competitive advantage.

Significant_accounting_policie

Significant accounting policies	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Organization, Consolidation and Presentation of Financial Statements Disclosure and Significant Accounting Policies [Text Block]	2	Significant accounting policies:
	(a)	Basis of presentation:
	The consolidated financial statements include the accounts of the Company, its wholly owned subsidiaries and variable interest entities (“VIEs”) for which the Company is considered the primary beneficiary.  All intercompany balances and transactions have been eliminated on consolidation.
	These consolidated financial statements are presented in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”).
	The Company has sustained net losses over the past several years and as at December 31, 2014 have an accumulated a deficit of $765.0 million. As at December 31, 2014 the Company has cash and cash equivalents of $93.3 million. The Company’s ability to continue as a going concern is dependent on its available cash, its ability to find new sources of financing or raise cash through the sale of assets while in pursuit of operating profitability. Over the past year, the Company has taken immediate actions to right-size the business structure and reduce expenses through activities including staff reductions and deferral of non-core development programs.  Management believes these factors will contribute toward achieving profitability, though further expense reductions may be required. However, there can be no assurance that the Company will be successful in achieving its objectives. Management believes that the cash balances available as of December 31, 2014, combined with cost cutting measures in place and its ability to find new sources of financing or raise cash through the sale of assets subsequent to the balance sheet date, provides sufficient funds for the Company to meet its obligations beyond the next 12 months. The accompanying financial statements do not include any adjustments that might be necessary if the Company is unable to continue as a going concern.
	(b)	Foreign currency translation:
	The Company’s reporting currency for its consolidated financial statement presentation is the United States dollar.  The functional currencies of the Company’s operations and subsidiaries include the following: United States, Canadian and Australian dollar, Euro, Chinese Renminbi (“RMB”), and Swedish Krona.  The Company translates assets and liabilities of non-US dollar functional currency operations using the period end exchange rates,  shareholders’ equity balances using the weighted average of historical exchange rates, and revenues and expenses using the monthly average rate for the period with the resulting exchange differences recognized in other comprehensive income.
	Transactions that are denominated in currencies other than the functional currency of the Company’s operations or its subsidiaries are translated at the rate in effect on the date of the transaction.  Foreign currency denominated monetary assets and liabilities are translated to the applicable functional currency at the exchange rate in effect on the balance sheet date.  Non-monetary assets and liabilities are translated at the historical exchange rate.  All foreign exchange gains and losses are recognized in the statement of operations, except for the translation gains and losses arising from available-for-sale instruments, which are recorded through other comprehensive income until realized through disposal or impairment.
	Except as otherwise noted, all amounts in these financial statements are presented in U.S. dollars.  For the periods presented, the Company used the following exchange rates:
			Period end exchange rate as at:					Average for the year ended:
			December 31, 2014			December 31, 2013		December 31, 2014		December 31, 2013
	Canadian dollar			0.86			0.94		0.91		0.97
	Australian dollar			0.82			0.89		0.9		0.97
	Euro			1.21			1.38		1.33		1.33
	RMB			0.16			0.17		0.16		0.16
	Swedish Krona			0.13			0.16		0.15		0.15
	(c)	Cash and cash equivalents:
	Cash and cash equivalents includes cash, term deposits, bankers acceptances and guaranteed investment certificates with maturities of ninety days or less when acquired.  Cash equivalents are considered as held for trading and recorded at fair value with changes in fair value recognized in the consolidated statements of operations.
	(d)	Short-term investments:
	Short-term investments, consisting of investment grade commercial paper, banker acceptances, bearer deposit notes, guaranteed investment certificates and other term deposits, are considered available for sale and recorded at fair value with changes in fair value recognized in accumulated other comprehensive income until realized.  A decline in value that is considered other than temporary is recognized in net loss for the period.
	(e)	Accounts receivable, net:
	Accounts receivable are measured at amortized cost.  The Company maintains allowances for doubtful accounts for estimated losses resulting from the inability of its customers to make required payments. Management considers the following factors when determining the collectibility of specific customer accounts: customer credit-worthiness, past transaction history with the customer, current economic industry trends, and changes in customer payment terms. Past due balances over 90 days and other higher risk amounts are reviewed individually for collectibility. If the financial condition of the Company’s customers were to deteriorate, adversely affecting their ability to make payments, additional allowances would be required. Based on management’s assessment, the Company provides for estimated uncollectible amounts through a charge to earnings and a credit to a valuation allowance. Balances that remain outstanding after the Company has used reasonable collection efforts are written off through a charge to the valuation allowance and a credit to accounts receivable.
	(f)	Inventories:
	The Company’s inventories consist of the Company’s fuel system products (finished goods), work-in-progress, purchased parts and assembled parts. Inventories are recorded at the lower of cost and net realizable value.  Cost is determined based on the lower of weighted average cost and net realizable value.  The cost of fuel system product inventories, assembled parts and work-in-progress includes materials, labour and production overhead including depreciation. The Company provides inventory write-downs based on excess and obsolete inventories determined primarily by future demand forecasts. In addition, the Company records a liability for firm, noncancelable, and unconditional purchase commitments with manufacturers for quantities in excess of the Company’s future demand forecast consistent with its valuation of excess and obsolete inventory.
	(g)	Property, plant and equipment:
	Property, plant and equipment are stated at cost.  Depreciation is provided as follows:
	Assets		Basis		Rate
	Buildings		Straight-line		15 years
	Computer equipment and software		Straight-line		3 years
	Furniture and fixtures		Straight-line		5 years
	Machinery and equipment		Straight-line		8 – 10 years
	Leasehold improvements		Straight-line		Lease term
	(h)	Long-term investments:
	The Company accounts for investments in which it has significant influence, including VIEs for which the Company is not the primary beneficiary, using the equity basis of accounting.  Under the equity method, the Company recognizes its share of income from equity accounted investees in the statement of operations with a corresponding increase in long-term investments.  Any dividends paid or payable are credited against long-term investments.
	(i)	Financial liabilities:
	Accounts payable and accrued liabilities, short-term debt and long-term debt are measured at amortized cost.  Transaction costs relating to long-term debt are deferred in other assets on initial recognition and are amortized using the effective interest rate method.
	(j)	Research and development costs:
	Research and development costs are expensed as incurred and are recorded net of government funding received or receivable.
	(k)	Government assistance:
	The Company periodically applies for financial assistance under available government incentive programs, which is recorded in the period it is received or receivable.  Government assistance relating to the purchase of property, plant and equipment is reflected as a reduction of the cost of such assets.  Government assistance related to research and development activities is recorded as a reduction of the related expenditures.
	(l)	Intangible assets:
	Intangible assets consist primarily of the cost of intellectual property, trademarks, technology, customer contracts and non-compete agreements.  Intangible assets are amortized over their estimated useful lives, which range from 5 to 20 years.
	(m)	Impairment of long-lived assets:
	The Company reviews its long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of the assets may not be recoverable.  If such conditions exist, assets are considered impaired if the sum of the undiscounted expected future cash flows expected to result from the use and eventual disposition of an asset is less than its carrying amount.  An impairment loss is measured at the amount by which the carrying amount of the asset exceeds its fair value.  When quoted market prices are not available, the Company uses the expected future cash flows discounted at a rate commensurate with the risks associated with the recovery of the asset as an estimate of fair value.
	(n)	Goodwill impairment:
	Goodwill is recorded at the time of purchase for the excess of the amount of the purchase price over the fair values of the identifiable assets acquired and liabilities assumed.  Goodwill is not amortized and instead is tested at least annually for impairment, or more frequently when events or changes in circumstances indicate that goodwill might be impaired.  This impairment test is performed annually at November 30.  Future adverse changes in market conditions or poor operating results of underlying assets could result in an inability to recover the carrying value of the goodwill, thereby possibly requiring an impairment charge.
	A two-step test is used to identify a potential impairment and to measure the amount of impairment, if any.  The first step is to compare the fair value of the reporting unit with its carrying amount, including goodwill.  If the fair value of the reporting unit exceeds its carrying amount, goodwill is considered not impaired; otherwise, goodwill is impaired and the loss is measured by performing step two.  Under step two, the impairment loss is measured by comparing the implied fair value of the reporting unit goodwill with the carrying amount of goodwill.
	Fair value is determined using widely accepted valuation techniques, which may include discounted cash flows and market multiple analyses.  These types of analyses contain uncertainties because they require management to make assumptions and to apply judgment to estimate industry economic factors and the profitability of future business strategies.
	(o)	Warranty liability:
	Estimated warranty costs are recognized at the time the Company sells its products and are included in cost of revenue.  The Company provides warranty coverage on products sold for a period ending two years from the date the products are put into service by customers.  Warranty liability represents the Company’s best estimate of warranty costs expected to be incurred during the warranty period.  Furthermore, the current portion of warranty liability represents the Company’s best estimate of the costs to be incurred in the next twelve-month period.  The Company uses historical failure rates and cost to repair defective products to estimate the warranty liability.  New product launches require a greater use of judgment in developing estimates until claims experience becomes available.  Product specific experience is typically available four or five quarters after product launch, with a clear experience trend not evident until eight to twelve quarters after launch.  The Company records warranty expense for new products upon shipment using a factor based upon historical experience from previous engine generations in the first year, a blend of actual product and historical experience in the second year and product specific experience thereafter.  The amount payable by the Company and the timing will depend on actual failure rates and cost to repair failures of its products.  Since a number of the Company’s products are new in the market, historical data may not necessarily reflect actual costs to be incurred and may result in significant fluctuations in the warranty liability.
		(p)	Extended warranty:
	The Company sells extended warranty contracts that provide coverage in addition to the basic warranty coverage.  Proceeds from the sale of these contracts are deferred and amortized over the extended warranty period commencing at the end of the basic warranty period.  On a periodic basis, management reviews the estimated costs expected to be incurred related to servicing these contracts and recognizes a loss to the extent such costs exceed the related deferred revenue. Extended warranty costs are expensed as period costs as incurred.
		(q)	Revenue recognition:
	Product revenue
	The Company’s primary source of revenue is from the sale of kits, Westport LNG systems and parts, and Westport CNG and LPG fuel systems for OEMs in the light-duty automotive and industrial markets.  Product revenue is recognized when contractual terms are agreed upon, the price is fixed or determinable, the products are shipped and title passes to the customer and collectability is reasonably assured.
	Revenue from research and development
	The Company also earns service revenue from research and development arrangements under which the Company provides contract services relating to developing natural gas engines or biogas engines for use in products and providing ongoing development services to assist with the development and commercialization of products.  These contracts provide for the payment for services based on our achieving defined milestones or on the performance of work under product development programs.  Revenues are recognized using the milestone method based on assessment of progress achieved against the defined milestones.  Revenue may also be recognized using the proportionate performance method of accounting based on the performance of work under the research and development arrangement.  There is a risk that a customer may ultimately disagree with our assessment of the progress achieved against milestones or that our estimates of the percentage of work completed could change. Should this occur, the revenues recognized in the period might require adjustment in a subsequent period. All costs incurred related to revenue earned from research and development arrangements are recorded as research and development expense as incurred.
	Revenue from contracts
	The Company earns revenue under certain contracts to provide engineering development services.  These contracts provide for the payment for services based on the performance of work under product development programs.  Revenues are recognized under these contracts based on the percentage of completion method of accounting.  The components to measure percentage of completion are complex and subject to many variables.  Components may include estimated costs to complete a contract, estimated hours to completion or management’s assessment of work to be performed.  When estimates of total costs to be incurred on a contract exceed total estimates of revenue to be earned, a provision for the entire loss on the contract is recorded in the period the loss is determined.  There is a risk that the estimated percentage of completion of a contract may change, which may result in an adjustment to previously recognized revenues. All costs incurred related to revenue earned from contracts are recorded in cost of products sold.
	Arrangements with customers may include multiple deliverables, including any combination of products, services, and licenses. In these arrangements, the Company allocates revenue to all deliverables based on their relative selling prices. The Company uses a hierarchy to determine the selling price to be used for allocating revenue to deliverables: (a) vendor-specific objective evidence of fair value (VSOE), (b) third-party evidence of selling price (TPE), and (c) best estimate of selling price (BESP), which are determined as follows:
	VSOE-In limited circumstances are products sold separately in stand-alone arrangements.  In determining VSOE, the Company requires that a substantial majority of the selling prices for a product or service falls within a reasonably narrow pricing range, generally evidenced by the pricing rates of approximately 85% of such historical stand-alone transactions falling within plus or minus 10% of the median rate. In addition, the Company considers the geographies in which the products or services are sold, major product and service groups, customer classification, and other environmental or marketing variables in determining VSOE.
	TPE-VSOE exists only when the Company sells the deliverable separately. When VSOE does not exist, the Company attempts to determine TPE based on competitor prices for similar deliverables when sold separately. Generally, the Company’s go-to-market strategy for many of its products differs from that of its peers and its offerings contain a significant level of customization and differentiation such that the comparable pricing of products with similar functionality sold by other companies cannot be obtained. Furthermore, the Company is unable to reliably determine what similar competitor products’ selling prices are on a stand-alone basis. Therefore, the Company is typically not able to determine TPE.
	BESP-The objective of BESP is to determine the price at which the Company would transact a sale if the product or service were sold on a stand-alone basis. When both VSOE and TPE do not exist, the Company determines BESP by first collecting all reasonably available data points including sales, cost and margin analysis of the product, and other inputs based on the Company’s normal pricing practices. Second, the Company makes any reasonably required adjustments to the data based on market and Company-specific factors. Third, the Company stratifies the data points, when appropriate, based on customer, magnitude of the transaction and sales volume.
	Once elements of an arrangement are separated into more than one unit of accounting, revenue is recognized for each separate unit of accounting based on the nature of the revenue as described above.
Changes in cost estimates and the fair values of certain deliverables could negatively impact the Company’s operating results. In addition, unforeseen conditions could arise over the contract term that may have a significant impact on the Company’s operating results.
License revenue
Revenue from technology license fees is recognized over the duration of the licensing agreement.  Amounts received in advance of the revenue recognition criteria being met are recorded as deferred revenue.
(r)	Income taxes:
The Company accounts for income taxes using the asset and liability method.  Under this method, deferred income tax assets and liabilities are determined based on the temporary differences between the accounting basis and tax basis of the assets and liabilities and for loss carry-forwards, tax credits and other tax attributes, using the enacted tax rates in effect for the years in which the differences are expected to reverse.  The effect of a change in tax rates on the deferred income tax assets and liabilities is recognized in income in the period that includes the enactment date.
The Company recognizes deferred income tax assets to the extent the assets are more-likely-than-not to be realized. In making such a determination the Company considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies, and results of recent operations. If it is determined that, based on all available evidence, it is more-likely-than-not that some or all of the deferred income tax assets will not be realized, a valuation allowance is provided to reduce the deferred income tax assets.
The Company uses a two-step process to recognize and measure the income tax benefit of uncertain tax positions taken or expected to be taken in a tax return. The tax benefit from an uncertain tax position is recognized if it is more-likely-than-not that the position will be sustained upon examination by a tax authority based solely on the technical merits of the position. A tax benefit that meets the more-likely-than-not recognition threshold is measured as the largest amount that is greater than 50% likely to be realized upon settlement with the tax authority. To the extent a full benefit is not expected to be realized, an income tax liability is established. Any change in judgment related to the expected resolution of an uncertain tax position is recognized in the year of such a change.

Accounting_Changes

Accounting Changes	12 Months Ended
	Dec. 31, 2014
Accounting Changes and Error Corrections [Abstract]
Accounting Changes and Error Corrections [Text Block]	3	Accounting Changes
	(a)	Adoption of new accounting standards:
	Income taxes:
	In July 2013, the FASB issued ASU No. 2013-11, Income Taxes (Topic 740): Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carry forward, a Similar Tax Loss, or a Tax Credit Carryforward Exists (“ASU 2013-11”).  ASU 2013-11's purpose is to eliminate the diversity in the presentation of unrecognized tax benefits.  Entities are required to present any unrecognized tax benefit as a reduction to a deferred tax asset for a net operating loss carryforward, a similar tax loss, or a tax credit carryforward.  In circumstances where a net operating loss carryforward, a similar tax loss, or a tax credit carryforward is not available at the reporting date under the tax law of the applicable jurisdiction to settle any additional income taxes that would result from the disallowance of a tax position or where the entity does not intend to use the deferred tax asset for this purpose, the unrecognized tax benefit should be presented in the financial statements as a liability and should not be combined with deferred tax assets.  This new guidance was applied prospectively effective on January 1, 2014.  The adoption of this update did not have a material impact on the Company's consolidated financial statements.
	(b)	New accounting pronouncements:
	Revenue:
	In May 2014, Financial Accounting Standards Board (“FASB”) issued ASU 2014-09, Revenue From Contracts With Customers (“Topic 606”). Topic 606 removes inconsistencies and weaknesses in revenue requirements, provides a more robust framework for addressing revenue issues, improves comparability of revenue recognition practices across entities, industries, jurisdictions and capital markets, provides more useful information to users of financial statements through improved disclosure requirements and simplifies the preparation of financial statements by reducing the number of requirements to which an entity must refer. The guidance in this update supersedes the revenue recognition requirements in Topic 605, Revenue Recognition, and most industry-specific guidance throughout the Industry Topics of the Codification. Additionally, this update supersedes some cost guidance included in Subtopic 605-35, Revenue Recognition - Construction-Type and Production-Type Contracts. Topic 606 is effective for public entities with reporting periods beginning after December 15, 2016. Early adoption is not permitted. The Company has not yet evaluated the impact of the adoption of this new standard.
	Going Concern:
	In August 2014, the FASB issued ASU 2014-15. Presentation of Financial Statements - Going Concern outlining management’s responsibility to evaluate whether there is substantial doubt about an entity’s ability to continue as a going concern, along with the required disclosures.  ASU 2014-15 is effective for the annual period ending after December 15, 2016 with early adoption permitted.  The Company does not anticipate a material impact to the Company’s financial statements as a result of this change.

Business_Combinations

Business Combinations	12 Months Ended
	Dec. 31, 2014
Business Combinations [Abstract]
Business Combination Disclosure [Text Block]	4.  Business Combinations
	(a)	Acquisition of Prins Autogassystemen Holding B.V.
	On December 2, 2014 (“the acquisition date”), the Company acquired 100% of the outstanding shares of Prins Autogassystemen Holding B.V. (“Prins”) for a base purchase price of EUR 12,200 ($15,017). The Company paid cash of EUR 2,500 ($3,112) and assumed debt of EUR 9,700 ($11,905). The results of Prins's consolidated operations have been included since December 2, 2014. Prins is a world leader in the development of alternative fuel systems and provides cost-effective and innovative solutions for a wide range of engine types.
	The Company recognized $342 of acquisition related costs in General and Administrative expense under the Corporate and Technology Investments segment during the year ended December 31, 2014.
	The estimated fair values of assets acquired and liabilities assumed are provisional and are based on the information that was available as of the acquisition date to estimate the fair value of assets acquired and liabilities assumed. The Company believes that information provides a reasonable basis for estimating the fair values of assets acquired and liabilities assumed, but the Company is waiting for additional information necessary to finalize those fair values. Therefore, the provisional measurements of fair value reflected are subject to change and such changes could be significant. The Company expects to finalize the valuation and complete the purchase price allocation as soon as practicable but no later than one year from the acquisition date.
	Consideration allocated to:
	Other tangible assets, including cash of $61		$	13,138
	Property, plant and equipment			3,824
	Intangible assets subject to amortization over 5 years			3,024
	Goodwill			3,221
	Total assets acquired		$	23,207
	Less:
	Current liabilities			7,211
	Deferred income tax liabilities			979
	Debt assumed (note 13b and c)			11,905
			$	20,095
	Total net assets acquired		$	3,112
	Consideration:
	Paid to sellers		$	3,112
	Intangible Assets
	The fair value of intangible assets is $3,024 and is assigned to customer relationships.  The intangible assets will be amortized over their estimated useful life of 5 years.
	Inventory
	The fair value of $4,975 assigned to inventory was based on estimated selling prices and selling costs associated with the inventory.
	Goodwill
	Of the total consideration paid, $3,221 has been allocated to goodwill. The entire goodwill recognized is assigned to the Applied Technologies and is not deductible for tax purposes.
	Land and Building
	The fair value of $3,824 assigned to land and building was based on valuations of similar buildings in the area and will be amortized over its estimated useful life of 15 years.
	The consolidated financial statements reflect consolidated revenue and net loss for Prins of $1,196 and $(301), respectively, from December 2, 2014 to December 31, 2014.
	Pro forma results
	The following unaudited supplemental pro forma information presents the consolidated financial results as if the acquisition of Prins had occurred on January 1, 2013.  This supplemental pro forma information has been prepared for comparative purposes and does not purport to be indicative of what would have occurred had the acquisition been made on January 1, 2013, nor are they indicative of any future results.
			Years ended December 31,
			2014		2013
	Revenue
	Revenue for the period		$	130,569	$	164,032
	Add: BAF - see (note 4(b))			—		7,249
	Add: Prins			30,993		30,885
	Pro forma revenue for the period		$	161,562	$	202,166
	Net Loss
	Net loss for the period		$	-149,618	$	-185,410
	Add: BAF - see (note 4(b))			—		-4,038
	Add: Prins			91		9,164
	Pro forma net loss for the period		$	-149,527	$	-180,284
	These amounts have been calculated after applying the Company’s accounting policies and adjusting the results of Prins to reflect the additional depreciation and amortization that would have been charged assuming the fair value adjustments to property, plant and equipment and intangible assets had been applied on January 1, 2013, together with the consequential tax effects.
	(b)	Acquisition of BAF Technologies, Inc. (“BAF”):
	On June 28, 2013 (“the acquisition date”), the Company acquired 100% of the outstanding common shares of BAF and its subsidiary, ServoTech Engineering, Inc. (“ServoTech”) from Clean Energy Fuels Corp. (“Clean Energy”). The results of BAF’s consolidated operations have been included since July 1, 2013 in these consolidated financial statements in the On-Road Systems segment. BAF is a natural gas vehicle business that supports customers with vehicle conversions under Ford’s Qualified Vehicle Modifier (“QVM”) program. ServoTech is an engineering company that provides a total engineering solution from initial concept phase to prototype hardware and validation.
	Pursuant to the Stock Purchase Agreement, the acquisition was settled with 816,460 of the Company’s common shares. The number of shares transferred was determined using the 10-day volume weighted average price (VWAP) per share prior to and including the acquisition date ($30.62 per share). Of the 816,460 common shares, 718,485 shares, with a fair value of $24,091, were issued on the acquisition date and 97,975 shares (“Holdback shares”), with a fair value of $3,285, were issued. The fair value of the shares transferred or to be transferred was determined by the closing share price on the acquisition date ($33.53 per share).
	As part of the business acquisition, the Company entered into a marketing agreement (“Marketing Agreement”) with Clean Energy, effective on the acquisition date for a period of two years. The Company was required to make a cash payment of $5,000 to Clean Energy in March 2014. Under the terms of the Marketing Agreement, Clean Energy will provide products and services to the Company.
	The products and services received pursuant to the Marketing Agreement have been accounted for as a separate transaction from the business combination and the Company has determined the fair value of these products and services to be $2,678. The fair value has been allocated to the products and services and will be recognized when the goods are received and services performed. The fair value of the products and services of the Marketing Agreement was determined using Level 1 and Level 2 inputs.
	The excess of the consideration payable of $5,000 and the fair value of the goods and services to be received separate from the business combination of $2,322 has been included as purchase consideration for the acquisition of BAF.
	The following table summarizes management’s final fair market valuation of the assets acquired and liabilities assumed at the acquisition date based on the results of a valuation report issued by a third-party valuation firm.
	Consideration allocated to:
	Other tangible assets, including cash of $1,178		$	9,116
	Property, plant and equipment			905
	Intangible assets subject to amortization over 3 to 10 years			7,729
	Goodwill			18,542
	Total assets acquired			36,292
	Less: total liabilities			-6,594
	Total net assets acquired		$	29,698
	Consideration:
	Payable to Clean Energy		$	2,322
	Common shares issued			24,091
	Common shares to be issued			3,285
			$	29,698
	The Company recognized $493 of acquisition related costs in General and Administrative expense under the Corporate and Technology Investments segment during the year ended December 31, 2013.
Intangible Assets
The fair values for specifically identifiable intangible assets by major asset class are as set forth below.
				Weighted average
		Assigned fair value		amortization period
Customer relationships		$	6,350		8 years
Core technology			160		10 years
Other intangibles			1,219		3 years
Total		$	7,729		7 years
Inventory
The fair value of $5,792 assigned to inventory was based on assumptions about the selling prices and selling costs associated with the inventory.
Deferred Income taxes
The Company recognized a deferred income tax liability of $296 relating to the difference in book and tax bases of acquired assets.
Goodwill
Of the total consideration paid, $18,542 has been allocated to goodwill.  The entire goodwill amount recognized is assigned to the On-Road Systems segment.  The goodwill recognized is attributable primarily realizing expected synergies that are specific to the Company’s business.  The goodwill is not deductible for tax purposes.
The consolidated financial statements reflect consolidated revenue and net loss for BAF of $17,097 and $3,512, respectively, from June 28, 2013 to December 31, 2013.
pro froma results
The following unaudited supplemental pro forma information presents the consolidated financial results as if the acquisition of BAF had occurred on January 1, 2012.  This supplemental pro forma information has been prepared for comparative purposes and does not purport to be indicative of what would have occurred had the acquisition been made on January 1, 2012, nor are they indicative of any future results.
		Years ended December 31,
		2013		2012
Revenue		$	171,281	$	181,972
Net loss		$	-189,448	$	-100,946
These amounts have been calculated after applying the Company’s accounting policies and adjusting the results of BAF to reflect the additional depreciation and amortization that would have been charged assuming the fair value adjustments to property, plant and equipment and intangible assets had been applied on January 1, 2012, together with the consequential tax effects.

Accounts_Receivable

Accounts Receivable	12 Months Ended
	Dec. 31, 2014
Receivables [Abstract]
Loans, Notes, Trade and Other Receivables Disclosure [Text Block]	5	Accounts Receivable:
			December 31, 2014		December 31, 2013
	Customer trade receivable		$	43,256	$	54,017
	Government funding receivable			38		483
	Due from joint venture (note 20)			2,538		3,621
	Other receivables			3,269		2,689
	Income tax receivable			499		77
	Allowance for doubtful accounts			-2,751		-1,572
			$	46,849	$	59,315

Inventories

Inventories	12 Months Ended
	Dec. 31, 2014
Inventory Disclosure [Abstract]
Inventory Disclosure [Text Block]	6	Inventories:
			December 31, 2014		December 31, 2013
	Purchased parts		$	28,227	$	23,228
	Work-in-process			4,879		10,770
	Finished goods			8,718		6,628
			$	41,824	$	40,626
	During the year ended December 31, 2014, the Company recorded write-downs to net realizable value of approximately $2,102 (year ended December 31, 2013 - $4,925; year ended December 31, 2012 - $233).

Longterm_investments

Long-term investments	12 Months Ended
	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Cost and Equity Method Investments Disclosure [Text Block]	7	Long-term investments:
			December 31, 2014		December 31, 2013
	Weichai Westport Inc. (a)		$	18,791	$	14,534
	Cummins Westport Inc. (b)			13,196		7,191
	Other equity accounted for investees			1,337		403
			$	33,324	$	22,128
	(a)   Weichai Westport Inc.:
	On July 3, 2010, the Company invested $4,316 under an agreement with Weichai Holding Group Co. Ltd. and Hong Kong Peterson (“CNG”) Equipment Ltd. to form Weichai Westport Inc. (“WWI”). On October 11, 2011, the Company invested an additional $955 in WWI. The Company has a 35% equity interest in WWI.
	For the year ended December 31, 2014, the Company recognized its share of WWI’s income of $6,027 (year ended December 31, 2013 - $4,264; year ended December 31, 2012 - $2,881), as income from investment accounted for by the equity method.
	Assets, liabilities, revenue and expenses of WWI as of and for the periods presented are as follows:
			December 31,		December 31,
			2014		2013
	Current assets:
	Cash and short-term investments		$	11,734	$	4,696
	Accounts receivable			72,121		31,967
	Inventory			83,594		80,412
	Other current assets			1,249		176
	Long-term assets
	Property, plant and equipment			5,736		7,021
	Deferred income tax assets			7,781		6,874
	Total assets		$	182,215	$	131,146
	Current liabilities:
	Accounts payable and accrued liabilities		$	128,838	$	93,016
	Total liabilities		$	128,838	$	93,016
			Years ended December 31,
			2014		2013		2012
	Product revenue		$	618,465	$	466,580	$	272,086
	Cost of revenue and expenses:
	Cost of product revenue			565,943		429,238		247,299
	Operating expenses			32,227		22,846		15,022
				598,170		452,084		262,321
	Income before income taxes			20,295		14,496		9,765
	Income tax expense			3,076		2,315		1,536
	Income for the period		$	17,219	$	12,181	$	8,229
	(b)           Cummins Westport Inc.:
	The Company entered into a joint venture with Cummins on March 7, 2001. On December 16, 2003, the Company and Cummins amended the joint venture agreement (“JVA”) focusing CWI on developing markets for alternative fuel engines. In addition, the two companies signed a Technology Partnership Agreement that creates a flexible arrangement for future technology development between Cummins and the Company.
	On February 20, 2012, the JVA was amended and restated to provide for, among other things, clarification concerning the scope of products within CWI. In addition, the parties have revised certain economic terms of the JVA.
	The joint venture has a term of ten years from the date of the JVA and can be terminated under certain circumstances before the end of the term, including in the event of a material breach of the agreement by, or in the event of a change of control of one of the parties.
	Prior to February 20, 2012, the Company and Cummins shared equally in the profits and losses of CWI. Under the new JVA, profits and losses are shared equally up to an established revenue baseline, then any excess profit will be allocated 75% to the Company and 25% to Cummins.
	The Company has determined that CWI is a variable interest entity ("VIE"). Cummins and Westport each own 50% of the common shares of CWI and have equal representation on the Board of Directors. No one shareholder has the unilateral power to govern CWI. The Board of Directors has power over the operating decisions and to direct other activities of CWI that most significantly impact CWI’s economic performance as set forth in the governing documents. As decision-making at the Board of Directors’ level requires unanimous approval, this power is shared. Accordingly neither party is the primary beneficiary.
	The Company has not historically provided and does not intend to provide financial or other support to CWI that the Company is not contractually required to provide.
	For the year ended December 31, 2014, the Company recognized its share of CWI’s income of $8,136 (year ended December 31, 2013 - $9,433; year ended December 31, 2012 - $13,232), as income from investment accounted for by the equity method.
	Assets, liabilities, revenue and expenses of CWI are as follows:
			December 31, 2014		December 31, 2013
	Current assets:
	Cash and short-term investments		$	107,415	$	73,736
	Accounts receivable			12,741		4,645
	Current portion of deferred income tax assets			21,967		13,958
	Other current assets			116		210
	Long-term assets:
	Property, plant and equipment			1,294		1,096
	Deferred income tax assets			29,408		21,698
	Total assets		$	172,941	$	115,343
	Current liabilities:
	Current portion of warranty liability		$	48,818	$	18,395
	Current portion of deferred revenue			8,029		5,478
	Accounts payable and accrued liabilities			6,419		7,772
				63,266		31,645
	Long-term liabilities:
	Warranty liability			43,983		49,174
	Deferred revenue			34,345		17,815
	Other long-term liabilities			2,771		2,400
				81,099		69,389
	Total liabilities		$	144,365	$	101,034
		Years ended December 31,
		2014		2013		2012
Product revenue		$	283,551	$	261,012	$	161,741
Parts revenue			53,683		49,639		36,274
			337,234		310,651		198,015
Cost of revenue and expenses:
Cost of product and parts revenue			270,832		246,403		136,575
Research and development			21,131		21,522		12,114
General and administrative			1,202		1,348		1,417
Sales and marketing			22,514		17,839		12,541
Foreign exchange (gain) loss			34		-7		-18
Bank charges, interest and other			805		607		472
			316,518		287,712		163,101
Income from operations			20,716		22,939		34,914
Interest and investment income			260		117		530
Income before income taxes			20,976		23,056		35,444
Income tax expense (recovery):
Current			21,514		24,600		16,362
Deferred			-15,719		-18,566		-6,517
			5,795		6,034		9,845
Income for the period		$	15,181	$	17,022	$	25,599

Variable_interest_entities

Variable interest entities	12 Months Ended
	Dec. 31, 2014
Variable Interest Entities [Abstract]
Variable Interest Entities [Text Block]	8	Variable interest entities:
	Cummins and Westport each own 50% of the common shares of CWI and have equal representation on the Board of Directors.  No one shareholder has the unilateral power to govern CWI.  The Board of Directors has power over the operating decisions and to direct other activities of CWI that most significantly impact CWI’s economic performance as set forth in the governing documents.  As decision-making at the Board of Directors’ level requires unanimous approval, this power is shared.  Accordingly, neither party is the primary beneficiary.
	Prior to February 20, 2012, the Company and Cummins shared equally in the profits and losses of CWI.  Under the new Joint Venture Agreement, profits and losses are shared equally up to an established revenue baseline, and then any excess profits will be allocated 75% to the Company and 25% to Cummins.  The Company has not historically provided and does not intend to provide financial or other support to CWI that the Company is not contractually required to provide.
	The carrying amount and maximum exposure to losses relating to VIEs in which the Company holds a significant variable interest but is not the primary beneficiary, and which have not been consolidated, were as follows:
			Balance at December 31, 2014				Balance at December 31, 2013
			Carrying		Maximum		Carrying		Maximum
			amount		exposure to		amount		exposure
					loss				to loss
	Equity method investment		$	13,196	$	13,196	$	7,191	$	7,191
	Accounts receivable			2,538		2,538		3,621		3,621

Property_plant_and_equipment

Property, plant and equipment	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment Disclosure [Text Block]	9	Property, plant and equipment:
					Accumulated		Net book
	December 31, 2014		Cost		depreciation		value
	Land and buildings		$	3,015	$	—	$	3,015
	Computer equipment and software			9,277		7,063		2,214
	Furniture and fixtures			6,194		1,798		4,396
	Machinery and equipment			81,933		36,135		45,798
	Leasehold improvements			12,460		9,749		2,711
			$	112,879	$	54,745	$	58,134
					Accumulated		Net book
	December 31, 2013		Cost		depreciation		value
	Computer equipment and software		$	9,652	$	6,174	$	3,478
	Furniture and fixtures			6,608		1,692		4,916
	Machinery and equipment			86,067		32,099		53,968
	Leasehold improvements			15,084		10,097		4,987
			$	117,411	$	50,062	$	67,349
	As at December 31, 2014, equipment with a cost of $16,572 (December 31, 2013 - $18,788) and a net book value of $1,714 (December 31, 2013 - $5,465) is held under capital lease.
	Depreciation expense for the year ended December 31, 2014 was $14,106 (year ended December 31, 2013 - $12,246; year ended December 31, 2012 - $8,131).

Intangible_assets

Intangible assets	12 Months Ended
	Dec. 31, 2014
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Intangible Assets Disclosure [Text Block]	10	Intangible assets:
					Accumulated		Net book
	December 31, 2014		Cost		amortization		value
	Patents and trademarks		$	18,425	$	3,445	$	14,980
	Technology (1)			6,449		3,142		3,307
	Customer contracts (1)			13,762		4,163		9,599
	Other intangibles (1)			62		28		34
	Total		$	38,698	$	10,778	$	27,920
					Accumulated		Net book
	December 31, 2013		Cost		amortization		value
	Patents and trademarks		$	20,974	$	2,900	$	18,074
	Technology			7,468		2,796		4,672
	Customer contracts (2)			18,447		3,886		14,561
	Other intangibles			1,262		225		1,037
	Total		$	48,151	$	9,807	$	38,344
	(1) The Company reviews its long-lived assets for impairment including property, plant and equipment, and intangible assets whenever events and changes in circumstances indicate that the carrying amount of the assets may not be recoverable. Based on the revenue and operating results and decline in the oil price, the Company concluded there were impairment indicators requiring the performance of a long-lived assets impairment test for customer contracts, technology and other intangibles as of November 30, 2014. Accordingly non-cash impairment charges aggregating to $5,823 were recorded during the year ended December 31, 2014 which reduced the carrying values of technology by $115, customer contracts by $4,705 and other intangibles by $1,003 for the On-Road Systems segment.
	(2) During the year ended December 31, 2013, there was a significant decline in revenue from the lower than expected adoption rate of natural gas vehicles in our customer contracts.  An impairment analysis of the intangibles balance indicated that the carrying value exceeded the fair value of customer contracts.  Accordingly, an intangible impairment charge of $1,721 related to customer contracts in Sweden was recognized in the On-Road Systems segment.  The fair value of customer contracts was determined using the present value of expected cash flows discounted at a rate equivalent to a market participant’s weighted-average cost of capital.
	During the year ended December 31, 2014, amortization of $4,560 (December 31, 2013 - $4,042; year ended December 31, 2012 - $3,264) was recognized in the statement of operations.
	The expected amortization of intangible assets for fiscal 2015 to 2019 is $3,345 per year.

Goodwill

Goodwill	12 Months Ended
	Dec. 31, 2014
Goodwill Disclosure [Abstract]
Goodwill Disclosure [Text Block]	11	Goodwill:
	A continuity of goodwill is as follows:
			December 31, 2014		December 31, 2013
	Balance, beginning of period:		$	41,500	$	56,879
	Acquisition of Prins (note 4(a))			3,221		—
	Acquisition of BAF (note 4(b))			—		18,542
	Impairment losses			-18,543		-34,964
	Impact of foreign exchange changes			-2,826		1,043
	Balance, end of period		$	23,352	$	41,500
	An assessment of the carrying value of goodwill was conducted as of November 30, 2014. Based on the Company’s assessment, it was determined that the carrying amount of goodwill exceeded the implied fair value of goodwill by $18,543 in the On-Road Systems segment for the year ended December 31, 2014. The goodwill impairment charge was driven by the significant decline in the price of oil and a significant loss of revenue from the lower than expected adoption rate of natural gas vehicles.
	The remaining goodwill of $23,352 relates to the Applied Technologies segment. The fair value of the segment exceeded the carrying amount of goodwill.
	For the year ended December 31, 2013 an assessment of the carrying value of goodwill was conducted as of November 30, 2013.  Based on the Company’s assessment, it was determined that the carrying amount of goodwill exceeded the implied fair value of goodwill by $34,964.  A goodwill impairment loss of $30,067 and $4,897 was recorded in the Applied Technologies segment and the On-Road Systems segment, respectively, for the year ended December 31, 2013.  In the Applied Technologies segment, the goodwill impairment charge was driven by the adverse economic climate in Europe and other geographic markets and lower than anticipated revenues. In the On-Road Systems segment, the goodwill impairment charge was driven by a significant loss of revenue from lower than expected adoption rate of natural gas vehicles.
	For 2013 and 2014, the fair value of the reporting units was determined using the present value of expected future cash flows discounted at a rate equivalent to a market participant’s weighted-average cost of capital. The estimates and assumptions regarding expected future cash flows and the appropriate discount rates are in part based upon historical experience, financial forecasts and industry trends and conditions.

Accounts_payable_and_accrued_l

Accounts payable and accrued liabilities	12 Months Ended
	Dec. 31, 2014
Accounts Payable and Accrued Liabilities, Current [Abstract]
Accounts Payable and Accrued Liabilities Disclosure [Text Block]	12	Accounts payable and accrued liabilities:
			December 31, 2014		December 31, 2013
	Trade accounts payable		$	41,796	$	42,872
	Accrued payroll			5,270		7,937
	Accrued interest			1,237		893
	Income taxes payable			580		709
	Other payables (note 22b)			6,619		2,381
			$	55,502	$	54,792

Longterm_debt

Long-term debt	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Long-term Debt [Text Block]	13	Long-term debt:
			December 31, 2014		December 31, 2013
	Subordinated debenture notes (a)		$	46,491	$	33,847
	Senior financing (b)			15,910		15,941
	Senior revolving financing (c)			12,101		13,779
	Other bank financing (d)			2,646		403
	Capital lease obligations (e)			1,394		2,043
				78,542		66,013
	Current portion			-18,955		-53,025
			$	59,587	$	12,988
	(a)         On September 23, 2011, the Company raised $33,720 (CDN$36,000) through the issuance of debentures to Macquarie Private Wealth Inc. (“Macquarie”) on a private placement basis (the “Initial Debentures”). The Initial Debentures were unsecured and subordinated to senior indebtedness, matured on September 22, 2014, and bore interest at 9% per annum, payable in cash semi-annually in arrears on March 15 and September 15 of each year during the term, which commenced on March 15, 2012. The Initial Debentures were redeemable at the option of the Company at a price equal to $1,150 per $1,000 principal amount of the debentures on or before March 22, 2013. After March 22, 2013 and before maturity, the debentures were redeemedable at a price equal to $1,100 per $1,000 principal amount.
	On June 27, 2014, the Company raised $17,797 (CDN$19,000) through the issuance of debentures to Richardson GMP Limited (“RGMP”), formerly Macquarie Private Wealth Inc. on a private placement basis (the “Additional Debentures”). In conjunction with the issuance of the Additional Debentures, the Company amended the terms of the Initial Debentures (the “Amended Initial Debentures”). The Amended Initial Debentures are ranked pari passu with the Additional Debentures and both shall be treated as the same series of debentures (the “New Debentures”) with the same terms.  The New Debentures totaling  $51,517 (CDN$55,000) are composed of the Additional Debentures $17,797 (CDN$19,000) and the Amended Initial Debentures $33,720 (CDN$36,000). The New Debentures are unsecured and subordinated to senior indebtedness, mature on September 15, 2017, and bear interest at 9% per annum, payable in cash semi-annually in arrears on March 15 and September 15 of each year during the term. The New Debentures are redeemable at the option of the Company at a price equal to $1,150 per $1,000 principal amount of the debentures after September 15, 2015 and on or before March 15, 2016. After March 15, 2016 and before maturity, the debentures can be redeemed at a price equal to $1,100 per $1,000 principal amount.
	The New Debentures contain an extension option that will allow each debenture holder to have the option to extend, a maximum of six times, the maturity date for an additional period of six months provided that greater than CDN$10,000 of the aggregate principal amount of the New Debentures remain outstanding.
	The Company has performed the assessment of embedded derivatives within the New Debentures and concluded that there is an embedded derivative that requires bifurcation related to the extension option from the New Debentures. The extension option was deemed not clearly and closely related to the New Debentures and is separately accounted for as a standalone derivative. The Company recorded this embedded derivative as a non-current liability on its consolidated balance sheet. At issuance on June 27, 2014, the embedded derivative’s fair value was determined to be $1,169 (CDN$1,249),  which was recorded as a reduction to the carrying value of the New Debentures. The Company is accreting the carrying value of the debt to interest expense by using the effective interest method through to the maturity date of the New Debentures. The Company accreted $82 of the embedded derivative discount for the year ended December 31, 2014 (2013 $Nil ). The embedded derivative is subsequently adjusted to fair value at each reporting date, with the associated fair value loss (gain) recorded in interest and other income (loss). The fair value adjustment recorded  for the year ended December 31, 2014 was $(1,082) (2013 $Nil). The derivative liability is included in other long term liabilities on the consolidated balance sheets. The Company determined the fair value of the embedded derivative using the Interest Rate Option Pricing Method which incorporated the Black-Karasinski model.
	(b)
			December 31, 2014		December 31, 2013
	Emer Senior Financing (1)		$	9,376	$	15,941
	Prins Senior Financing (2)			3,630		—
	Prins Senior Mortgage Loan (3)			2,904		—
			$	15,910	$	15,941
	(1)         The Emer S.p.A (“Emer”) senior financing agreement bears interest at the 6-month Euribor plus  2.5% (2.7% as at December 31, 2014) and  is recorded at amortized cost using the effective interest rate method. Interest is paid semi-annually. The Company has pledged its interest in Emer as a general guarantee for its senior financing. The senior financing matures in 2017.
	(2)         A total of $7,521 Prins senior financing was assumed on the acquisition of Prins (note 4a). Principal of $3,891 was repaid on December 2, 2014. The senior financing agreement bears interest at the 3-month Euribor plus 3.5% (3.6% as at December 31, 2014). Interest is paid quarterly. The Company has pledged its interest in Prins as a general guarantee for its senior financing. The senior financing matures in 2016.
	(3)         The Prins senior mortgage loan was assumed on the acquisition of Prins (note 4a). The senior mortgage loan bears interest at 3-month Euribor plus 1% (1.1% as at December 31, 2014). Interest is paid quarterly. The Company has pledged its interest in Prins's building as a general guarantee for its senior mortgage loan. The senior mortgage loan matures in 2020.
	The principal repayment schedule of the senior financings are as follows for the years ended December 31:
			Emer Senior		Prins Senior		Prins Senior
			Financing		Financing		Mortgage Loan		Total
	2015		$	4,020	$	1,633	$	363	$	6,016
	2016			4,239		1,997		363		6,599
	2017			1,117		—		363		1,480
	2018			—		—		363		363
	2019 and thereafter			—		—		1,452		1,452
			$	9,376	$	3,630	$	2,904	$	15,910
	(c)         The senior revolving financing facility bears interest at the 6-month Euribor plus  2.5% (2.6% as at December 31, 2014) and will be repaid through two principal payments of $6,050 (€5,000) on March 31, 2016 and October 2, 2017. Interest is paid semi-annually. The Company has pledged its interest in Emer as a general guarantee for its senior revolving financing.
	Throughout the entire term of these financing arrangements, the Company is required to meet certain financial and non-financial covenants.  As of December 31, 2014, the Company is in compliance with all covenants under the financing arrangements.
	(d)
			December 31, 2014		December 31, 2013
	Emer other financing (1)		$	1,129	$	247
	Prins other financing (2)			1,424		—
	Other financing			93		156
			$	2,646	$	403
	(1)          Emer other financing consists of various unsecured bank financing arrangements that carry rates of interest ranging from 1.01% to  2.90% (2013 - 1.01% to 8.00%) and are payable on maturity dates ranging from June 23, 2015 to June 23, 2017.
	(2)         Prins other bank financing consists of a credit facility for maximum borrowings of €2,000. The credit facility bears interest at the 3 month Euribor + 3.5% (3.6% as of December 31, 2014). The credit facility is governed by an accounts receivable list requirement limiting such borrowings to 60% of accepted accounts receivable.
	(e)         The Company has capital lease obligations that have initial terms of three to five years at interest rates ranging from 3.07% to 4.93% (2013 - 3.07% to 7.32%).  The capital lease obligations require the following minimum annual principal payments during the respective fiscal years:
	2015		$	522
	2016			328
	2017			327
	2018			191
	2019			26
			$	1,394
	(f)         The Company has a credit facility for maximum borrowings of CDN$30,000.  The credit facility is governed by a margin requirement limiting such borrowings to a calculated amount based on cash and investments held with the creditor.  Borrowings may be drawn in the form of direct borrowings, letters of credit, foreign exchange forward contracts and overdraft loans.  Outstanding amounts on direct borrowings and overdraft loans drawn under this credit facility bear interest at the prime rate, and letters of credit bear interest at  0.75%  (2013 - 0.75%) per annum.  As at December 31, 2014 and 2013, no amounts of this credit facility were drawn.

Warranty_liability

Warranty liability	12 Months Ended
	Dec. 31, 2014
Product Warranties Disclosures [Abstract]
Product Warranty Disclosure [Text Block]	14	Warranty liability:
	A continuity of the warranty liability is as follows:
								Years ended December 31,
			2014		2013		2012
	Balance, beginning of period		$	28,845	$	6,380	$	4,401
	Warranty assumed on acquisition			1,952		582		—
	Warranty claims			-10,709		-5,397		-3,099
	Warranty accruals			2,734		4,153		5,303
	Change in estimate			—		22,837		—
	Impact of foreign exchange changes			287		290		-225
	Balance, end of period		$	23,109	$	28,845	$	6,380
	Less: Current portion			-9,696		-9,955		-2,072
	Long-term portion		$	13,413	$	18,890	$	4,308
	During the fourth quarter of 2013, a study of the historical data indicated that the cost to repair product defects continued to increase significantly primarily associated with our extended warranty contracts.  As a result, the Company recognized a change in estimate in our base warranty liability and a loss on our extended warranty contracts representing the excess of the estimated cost to service these contracts over the amount of the deferred revenue recognized associated with the contracts. The warranty liability was reviewed in the fourth quarter of 2014, and no change in estimate was required.

Other_longterm_liabilities

Other long-term liabilities	12 Months Ended
	Dec. 31, 2014
Other Liabilities Disclosure [Abstract]
Other Liabilities Disclosure [Text Block]	15	Other long-term liabilities:
			December 31,		December 31,
			2014		2013
	Severance indemnity (a)		$	1,519	$	1,547
	Contingent consideration payable related to AFV acquisition (b)			1,240		878
	Derivative Liability (note 13a)			86		—
	Deferred lease inducements			—		16
			$	2,845	$	2,441
	Current portion (included in accounts payable and accrued liabilities, other payables)			-1,240		—
			$	1,605	$	2,441
	(a)         Italian law requires companies to make a mandatory termination payment to employees. It is paid, as a lump sum, when the employment ends for any reason such as retirement, resignation or layoff. The severance indemnity liability is calculated in accordance with local civil and labour laws based on each employee’s length of service, employment category and remuneration. There is no vesting period or funding requirement associated with the liability. The liability recorded in the consolidated balance sheet is the amount that the employee would be entitled to if the employee terminates immediately. This liability for severance indemnities relates primarily to the Company’s employees in Italy.
	(b)         The total purchase price to acquire AFV also includes earn-out payments payable in the Company’s shares and tied to revenue and production milestones to be achieved no later than December 31, 2014. This contingent consideration has a fair value of $407 as at December 31, 2014 (December 31, 2013 - $427).
	The Company recorded compensation expense relating to two employees of AFV who receive earn-out payments in the Company’s shares that are tied to revenue and production milestones to be achieved no later than December 31, 2014 and contingent upon continuing employments. This contingent consideration has a fair value of $833 as at December 31, 2014 (December 31, 2013 - $451).
	Subsequent to year end 325,073 shares were issued in connection with the earn-out payments described above at $4.51CDN per share.

Government_assistance

Government assistance	12 Months Ended
	Dec. 31, 2014
Government Assistance Disclosure [Abstract]
Government Assistance Disclosure [Text Block]	16	Government assistance:
	From time to time, the Company enters into agreements for financial assistance with government agencies. During the years ended December 31, 2014, 2013 and 2012, government assistance of $892, $640 and $842 was received or receivable by the Company, respectively, which has been recorded as a reduction of the related research and development expenditures (Note 18).
	Under the terms of an agreement with the Industry Canada’s Industrial Technologies Office (“ITO”), from April 1, 2008 to March 31, 2015, inclusively, the Company is obligated to pay annual royalties equal to the greater of $1,164 (CDN$1,350) or 0.33% of the Company’s annual revenue provided that gross revenue exceeds $11,638 (CDN$13,500) in any of the aforementioned fiscal years. The royalty payment period may be extended until the earlier of March 31, 2018 or until cumulative royalties total $24,389 (CDN$28,200). For the year ended December 31, 2014, $1,481 (December 31, 2013 - $1,164) in royalties have been paid or are payable of which $1,470 (December 31, 2013 - $1,269) remains accrued in accounts payable and accrued liabilities as at December 31, 2014. As at December 31, 2014, cumulative royalties of CDN$8,364 have been paid.
	The Company is also obligated to pay royalties to the Government of Canada’s Department of Natural Resources equal to 1% of future revenue from engines for power generators until the earlier of ten years from the project completion date (August 30, 2004) or when cumulative royalties total CDN$1,000. As at December 31, 2014, there has been no revenue from the sales of engines for power generators; therefore, no royalty payments have been paid or are payable.

Share_capital_stock_options_an

Share capital, stock options and other stock-based plans	12 Months Ended
	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Disclosure of Compensation Related Costs, Share-based Payments [Text Block]	17	Share capital, stock options and other stock-based plans
	During the year ended December 31, 2014, the Company issued  652,046 common shares, net of cancellations, upon exercises of stock options and share units (year ended December 31, 2013 – 721,186 common shares; year ended December 31, 2012 – 513,490 common shares). The Company issues shares from treasury to satisfy stock option and share unit exercises.
	On June 30, 2014 the Company issued 94,914 common shares at a price of $33.53 per share (note 4(b)).
	On October 1, 2013, the Company issued 6,000,000 common shares at a price of $25.39 per share.  Gross proceeds totaled $152,340, and the Company incurred share issuance costs of $5,065.
	On June 28, 2013, the Company issued 718,485 common shares at a price of $33.53 per share as part of the consideration paid to acquire BAF (note 4(b)).
	On February 27, 2012, the Company issued 6,325,000 common shares at a price of $43.25 per share. Gross proceeds totaled $273,556, and the Company incurred share issuance costs of $8,126.
	At the Company's 2012 annual general meeting, the Company’s shareholders ratified and approved the Westport Omnibus Plan and reserved 8,000,000 common shares under this plan. Under the Westport Omnibus Plan, stock options, Restricted Share Units (“RSUs”) and Performance Share Units (“PSUs”) may be granted and are exercisable into common shares of the Company for no additional consideration.  Any employee, contractor, director or executive officer of the Company is eligible to participate in the Westport Omnibus Plan.
	The Executive and Senior Management Compensation Program sets out provisions where the RSUs and PSUs (together the “Units”) will be granted to the Company’s executive management if performance milestones are achieved as determined at the discretion of the Human Resources and Compensation Committee of the Company’s Board of Directors. These performance milestones are focused on achievement of key cash management, profitability and revenue growth objectives. Vesting periods and conditions for each Unit granted pursuant to the Westport Omnibus Plan are at the discretion of the Board of Directors and may include time based, share price or other performance targets.
	(a)	Stock options:
	The Company grants incentive stock options to employees, directors, officers and consultants. Stock options are granted with an exercise price of not less than the market price of the Company’s common shares on the date immediately prior to the date of grant. The exercise period of the options may not exceed eight years from the date of grant. Vesting periods of the options are at the discretion of the Board of Directors and may be based on fixed terms, achieving performance milestones or reaching specified share price targets.
	A summary of the status of the Company’s stock option plan as of December 31, 2014, December 31, 2013 and December 31, 2012 and changes during the periods then ended are presented as follows:
			December 31, 2014				December 31, 2013				December 31, 2012
					Weighted				Weighted				Weighted
					average				average				average
					exercise				exercise				exercise
			Number of		price		Number of		price		Number of		price
			shares		(CDN $)		shares		(CDN $)		shares		(CDN $)
	Outstanding, beginning of period			816,450	$	30.2		996,047	$	27.78		328,027	$	8.96
	Granted			—		—		—		—		770,727		33.77
	Exercised			-43,071		6.17		-111,986		6.8		-93,044		10.49
	Forfeited/expired			-741,156		33.82		-67,611		33.72		-9,663		33.36
	Outstanding, end of period			32,223	$	17.64		816,450	$	30.2		996,047	$	27.78
	Options exercisable, end of period			32,223	$	17.64		305,506	$	24.15		226,487	$	8.06
	During the year ended December 31, 2014, the Company recognized $1,764 (year ended December 31, 2013 - $2,094; year ended December 31, 2012 - $2,705) in stock-based compensation related to stock options.
	No stock options were granted during the year ended December 31, 2014 or the year ended December 31, 2013.
	The fair value of the options granted during the year ended December 31, 2012 was determined using the Black-Scholes option pricing formula simulation with the following weighted average assumptions: expected dividend yield - nil%, expected stock price volatility –   47.79%, risk free interest rate –   0.38%; expected life of options –  3 years. The weighted average grant date fair value was  $10.97 for options granted for the fiscal year ended December 31, 2012.
	As at December 31, 2014, an immaterial amount of compensation cost related to stock option awards has yet to be recognized in results from operations and will be fully recognized in 2015.
	(b)	Share units:
	The value assigned to issued Units and the amounts accrued are recorded as other equity instruments. As Units are exercised or vest and the underlying shares are issued from treasury of the Company, the value is reclassified to share capital.
	During the year ended December 31, 2014, the Company recognized $7,919 (year ended December 31, 2013 - $12,189; year ended December 31, 2012 – $9,763) of stock-based compensation associated with the Westport Omnibus Plan and the former Amended and Restated Unit Plan.
	A continuity of the Units issued under the Westport Omnibus Plan and the former Amended and Restated Unit Plan as of December 31, 2014, December 31, 2013 and December 31, 2012 are as follows:
			December 31, 2014				December 31, 2013				December 31, 2012
					Weighted				Weighted				Weighted
					average				average				average
					grant				grant				grant
					date fair				date fair				date fair
			Number of		value		Number of		value		Number of		value
			units		(CDN $)		units		(CDN $)		units		(CDN $)
	Outstanding, beginning of period			1,200,591	$	23.68		1,095,094	$	20.68		1,250,917	$	18.04
	Granted			5,792,162		10.54		742,140		30.21		185,705		35.99
	Exercised/Vested			-608,975		19.52		-448,526		24.44		-337,228		19.34
	Forfeited/expired			-1,045,905		21.75		-188,117		29.8		-4,300		19.67
	Outstanding, end of period			5,337,873	$	10.27		1,200,591	$	23.68		1,095,094	$	20.68
	Units outstanding and exercisable, end of period			142,166	$	11.67		224,638	$	11.2		262,615	$	8.86
	During 2014, 5,792,162 units (December 31, 2013 - 742,140) were granted to employees. This included 4,820,763 Restricted Share Units (RSUs (2013 - 352,485) and 971,399 Performance Share Units (PSUs) (2013 - 389,655). Values of RSU awards are determined based on the fair market value of the underlying Common Share on the date of grant. RSUs typically vest over a three year period so the actual value received by the individual depends on the share price on the day such RSUs are settled for Common Shares, not the date of grant. PSU awards do not have a certain number of Common Shares that will issue over time - it depends on future performance and the other conditions tied to the payout of the PSU. Values of PSU awards are determined based on the fair market value of the underlying Common Shares on the date of the grant (and generally assuming the issuance of one Common Share to be issued per PSU), calculated as the number of Common Shares issuable on settlement of the PSUs multiplied by a fair value as determined based on a Monte-Carlo simulation. During 2014, 963,575 PSUs (2013 - 54,876) were canceled or forfeited (2013 - 54,876).
	As at December 31, 2014, $30,102 of compensation cost related to Units awards has yet to be recognized in results from operations and will be recognized over a weighted average period of  2.42 years.
	(c)		Aggregate intrinsic values:
	The aggregate intrinsic value of the Company’s stock option awards and share units at December 31, 2014 and 2013 are as follows:
			December 31,		December 31,
			2014		2013
			CDN$		CDN$
	Stock options:
	Outstanding		$	—	$	1,337
	Exercisable			—		1,337
	Exercised			364		2,667
	Share units:
	Outstanding		$	23,433	$	24,960
	Exercisable			624		4,670
	Exercised			7,238		18,041
	(d)		Stock-based compensation:
	Stock-based compensation associated with the Unit plans and the stock option plan is included in operating expenses as follows:
			Years ended December 31,
			2014		2013		2012
	Research and development		$	1,749	$	2,195	$	2,251
General and administrative			5,884		10,201		6,752
Sales and marketing			2,050		1,887		3,465
		$	9,683	$	14,283	$	12,468

Research_and_development_expen

Research and development expenses	12 Months Ended
	Dec. 31, 2014
Research and Development [Abstract]
Research, Development, and Computer Software Disclosure [Text Block]	18	Research and development expenses:
	Research and development expenses are recorded net of government assistance received or receivable.  The research and development expenses had been incurred and program funding had been received or receivable are as follows:
		Years ended December 31,
		2014		2013		2012
	Research and development expenses	$	77,472	$	91,772	$	74,040
	Government assistance (note 16)		-892		-640		-842
	Research and development	$	76,580	$	91,132	$	73,198

Income_taxes

Income taxes	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income Tax Disclosure [Text Block]	19	Income taxes:
	(a)          The Company’s income tax provision differs from that calculated by applying the combined enacted Canadian federal and provincial statutory income tax rate of 26% for the year ended December 31, 2014 (year ended December 31, 2013 – 26%; nine months ended December 31, 2012 – 25%) as follows:
		Years ended December 31,
		2014		2013		2012
	Loss before income taxes	$	-150,197	$	-184,537	$	-97,036
	Expected income tax recovery		-39,051		-47,979		-24,259
	Increase (reduction) in income taxes resulting from:
	Non-deductible stock-based compensation		2,495		3,619		3,019
	Other permanent differences		-446		-2,562		-2,158
	Withholding taxes		969		590		1,187
	Change in enacted rates		—		—		62
	Foreign tax rate differences, foreign exchange and other adjustments		7,409		3,858		-382
	Non-taxable income from equity investment		-3,739		-2,851		-3,308
	Change in valuation allowance		25,784		37,391		27,577
	Goodwill impairment		4,748		8,807		—
	Change in uncertain tax position		1,252		—		—
	Income tax expense (recovery)	$	-579	$	873	$	1,738
	(b)	The significant components of the deferred income tax assets and liabilities are as follows:
		December 31, 2014		December 31, 2013
	Deferred income tax assets:
	Net loss carry forwards	$	129,258	$	108,083
	Intangible assets		4,091		4,276
	Property, plant and equipment		6,836		5,446
	Financing and share issuance costs		1,533		2,696
	Warranty liability		5,131		5,726
	Deferred revenue		1,416		1,191
	Inventory		2,336		2,017
	Research and development		2,733		2,341
	Other		7,262		6,410
	Total gross deferred income tax assets		160,596		138,186
	Valuation allowance		-152,207		-126,424
	Total deferred income tax assets		8,389		11,762
	Deferred income tax liabilities:
	Intangible assets		6,386		9,884
	Property, plant and equipment		2,754		3,132
	Other		774		650
	Total deferred income tax liabilities		9,914		13,666
	Total net deferred income tax liabilities	$	1,525	$	1,904
	Allocated as follows:
	Current deferred income tax assets		3,556		3,109
	Current deferred income tax liabilities		-398		-468
	Long-term deferred income tax assets		271		379
	Long-term deferred income tax liabilities		-4,954		-4,903
	Total net deferred income tax liabilities	$	-1,525	$	-1,883
	The valuation allowance is reviewed on a quarterly basis to determine if, based on all available evidence, it is more-likely-than-not that some or all of the deferred income tax assets will not be realized. The ultimate realization of deferred income tax assets is dependent on the generation of sufficient taxable income during the future periods in which those temporary differences are expected to reverse. If the evidence does not exist that the deferred income tax assets will be fully realized, a valuation allowance has been provided.
	The deferred income tax assets have been reduced by the uncertain tax position presented in note 19(f).
	The following is a summary of the changes in the deferred income tax asset valuation allowance:
		Year ended		Year ended
		December 31, 2014		December 31, 2013
	Beginning balance	$	126,424	$	89,033
	Additions		25,783		37,391
	Reductions		—		—
	Ending valuation allowance	$	152,207	$	126,424
	(c)	The components of the Company’s income tax expense (recovery) are as follows:
		Income tax expense (recovery)
		Net income (loss)
		before income
		taxes		Current		Deferred		Total
	Year ended December 31, 2014:
	Canada	$	-87,783		165		301	$	466
	United States		-49,577		8		—		8
	Italy		-3,834		521		-1,463		-942
	Other		-9,003		-88		-23		-111
		$	-150,197	$	606	$	-1,185	$	-579
Year ended December 31, 2013:
Canada	$	-99,188	$	444	$	89	$	533
United States		-31,019		56		-295		-239
Italy		-27,247		836		-311		525
Other		-27,083		78		-24		54
	$	-184,537	$	1,414	$	-541	$	873
Year ended December 31, 2012:
Canada	$	-93,688	$	1,339	$	53	$	1,392
United States		-1,589		-62		—		-62
Italy		-318		775		25		800
Other		-1,441		95		-487		-392
	$	-97,036	$	2,147	$	-409	$	1,738
(d)            The Company has loss carry-forwards in the various tax jurisdictions available to offset future taxable income as follows:
Expiring in:	2015		2016		2017		2018		2019		2020 and later		Total
Canada		$—		$—		$—		$—		$—	$	387,553,717	$	387,553,717
Italy		—		—		—		—		—		6,429,576		6,429,576
United States		—		—		—		—		—		55,353,513		55,353,513
Sweden		—		—		—		—		—		13,710,864		13,710,864
Other		—		—		—		1,085,596		6,725,731		7,834,119		15,645,446
Total		$—		$—		$—	$	1,085,596	$	6,725,731	$	470,881,789	$	478,693,116
(e)           The Company has not recognized a deferred income tax liability for the undistributed earnings of certain foreign subsidiaries which are essentially investments in those foreign subsidiaries and are permanent in duration.
(f)           The Company records uncertain tax positions in accordance with ASC No. 740, Income Taxes. As at December 31, 2014, the total amount of the Company’s uncertain tax benefits was $1,230 (year ended December 31, 2013 - nil). If recognized in future periods, the uncertain tax benefits would affect our effective tax rate. The Company files income tax returns in Canada, the U.S., Italy, and various other foreign jurisdictions. All taxation years remain open to examination by the Canada Revenue Agency, the 2009 to 2014 taxation years remain open to examination by the Internal Revenue Service and the Italian Revenue Agency, and various years remain open in the other foreign jurisdictions.
A reconciliation of the change in the reserves for uncertain tax positions from January 1, 2014 to December 31, 2014 is as follows:
Balance as of January 1, 2014	$	—
Tax positions related to the current year:
Additions		—
Reductions		—
	$	—
Tax positions related to prior years:
Additions		1,230
Reductions		—
Settlements		—
Lapses in statutes of limitations		—
Balance as of December 31, 2014	$	1,230

Related_party_transactions

Related party transactions	12 Months Ended
	Dec. 31, 2014
Related Party Transactions [Abstract]
Related Party Transactions Disclosure [Text Block]	20	Related party transactions:
	Pursuant to the amended and restated JVA, Westport engages in transactions with CWI.
	As at December 31, 2014, net amounts due from CWI total $2,538 (2013 - $3,621). Amounts receivable relate to costs incurred by Westport on behalf of CWI. The amounts are generally reimbursed by CWI to Westport in the month following the month in which the payable is incurred.  Cost reimbursements from CWI consisted of the following:
		Years ended December 31,
		2014		2013		2012
	Research and development	$	3	$	178	$	160
	General and administrative		1,548		1,351		2,621
	Sales and marketing		4,935		4,725		3,683
		$	6,486	$	6,254	$	6,464
	During the year ended December 31, 2014, interest of $nil (year ended December 31, 2013 - $nil; year ended December 31, 2012 - $114) was paid to CWI.

Service_and_other_revenue

Service and other revenue	12 Months Ended
	Dec. 31, 2014
Service And Other Revenue [Abstract]
Service And Other Revenue Disclosure [Text Block]	21	Service and other revenue:
	Service and other revenue for the year ended December 31, 2014 consisted of a one-time license revenue of $nil (year ended December 31, 2013 - $nil; year ended December 31, 2012 - $7,923) for the transfer of proprietary know-how, other fee payments of $1,480 (year ended December 31, 2013 - $1,484; year ended December 31, 2012 - $1,414), and service revenue of $11,074 (year ended December 31, 2013 - $14,547; year ended December 31, 2012 - $13,907) under existing development agreements. All costs associated with the development agreements were recorded as research and development expenses in the period incurred.
	During the year ended December 31, 2012, the Company entered into an agreement with an original equipment manufacturer (“OEM”) to co-develop natural gas technology for off-road equipment, including mining trucks and locomotives. Under the agreement, the Company provided its proprietary know-how related to the high pressure direct injection (“HPDI”) technology by granting a non-exclusive license to the OEM. The Company will also provide ongoing development services to the OEM to assist with the development and commercialization of products. These are considered to be multiple deliverables arrangements and the Company has determined that the license and the development services are separate units of accounting.

Commitments_and_contingencies

Commitments and contingencies	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies Disclosure [Text Block]	22	Commitments and contingencies:
	(a) Contractual Commitments
	The Company has obligations under operating lease arrangements that require the following minimum annual payments during the respective fiscal years:
	2015	$	3,946
	2016		4,978
	2017		5,890
	2018		4,969
	2019		4,960
	Thereafter		33,125
		$	57,868
	For the year ended December 31, 2014, the Company incurred operating lease expense of $3,879 (year ended December 31, 2013 - $5,675; year ended December 31, 2012 - $4,492).
	As at December 31, 2014, the Company’s wholly owned subsidiary Emer has provided a total amount of guarantees to third parties of $298, (December 31, 2013 - $342), which include guarantees to its customers for the completion of specific supplies.
	The Company is a party to a variety of agreements in the ordinary course of business under which it is obligated to indemnify a third party with respect to certain matters. Typically, these obligations arise as a result of contracts for sale of the Company’s product to customers where the Company provides indemnification against losses arising from matters such as product liabilities. The potential impact on the Company’s financial results is not subject to reasonable estimation because considerable uncertainty exists as to whether claims will be made and the final outcome of potential claims. To date, the Company has not incurred significant costs related to these types of indemnifications.
	The Company is engaged in certain legal actions in the ordinary course or business and believes that the ultimate outcome of these actions will not have a material adverse effect on our operating results, liquidity or financial position.
	(b) Purchase Commitments
	The Company purchases components from a variety of suppliers and contract manufacturers. During the normal course of business, in order to manage manufacturing lead times and help ensure adequate component supply, the Company enters into agreements with suppliers and contract manufacturers. A portion of our reported estimated purchase commitments arising from these agreements are firm, noncancelable, and unconditional commitments. The Company may be subject to penalties, and may lose important suppliers, if it is unable to meet its purchase commitments. In 2014, the Company entered into several long-term fixed price contracts to purchase parts to produce certain products. These contracts represent firm purchase commitments which are evaluated for potential market value losses. The Company estimated a loss on these firm purchase commitments with reference to the estimated future sales price of these products and recognized a provision for inventory purchase commitments of $4,106 in 2014. The provision is recognized in other payables in accounts payable and accrued liabilities (note 12).

Segmented_information

Segmented information	12 Months Ended
	Dec. 31, 2014
Segment Reporting [Abstract]
Segment Reporting Disclosure [Text Block]	23	Segmented information:
	The financial information for the Company’s business segments evaluated by the Company’s chief operating decision maker (“CODM”) includes the results of the CWI and WWI as if it were consolidated, which is consistent with the way Westport manages its business segments. As CWI and WWI are accounted for under the equity method of accounting, an adjustment is reflected in the tables below to reconcile the segment measures to the Company’s consolidated measures.
	The Company’s business operates in six reportable operating segments:
	- Applied Technologies, designs, produces, and sells compressed natural gas (CNG) and liquefied petroleum gas (LPG) components and subsystems for natural gas vehicles of all types;
	- On-Road Systems, engineers, designs, assembles and sells natural gas engine and vehicle systems for automotive, light commercial, and trucking;
	- Off-Road Systems, engineers, designs, and markets Westport proprietary natural gas technologies, including the Westport™ high pressure direct injection (HPDI) technology, Westport™ 2.4L industrial engines and fuel systems for the off-road, large-engine applications such as mine trucks, locomotives, workboats, and petroleum exploration equipment;
	- Corporate and Technology Investments, which includes corporate costs such as research and development, general and administrative, marketing, interest and other charges, foreign exchange and depreciation that cannot be attributed to a particular segment and are incurred by all segments;
	- CWI which serves the medium- to heavy-duty engine markets with spark ignited natural gas engines. The fuel for CWI engines is typically carried on vehicles as compressed natural gas or liquefied natural gas; and
	- WWI develops, manufactures, and sells advanced, alternative fuel engines and parts that are widely used in city bus, coach, and heavy-duty truck applications in China or exported to other regions globally.
	These reporting segments offer different products and services and are managed separately as each business requires different technology and marketing strategies.
	The accounting policies for the reportable segments are consistent with those described in note 2. The CODM evaluates segment performance based on the net operating income (loss), which is before income taxes and does not include depreciation and amortization, impairment charges, foreign exchange gains and losses, bank charges, interest and other expenses, interest and other income, and gain on sale of long-term investments. The Company did not record any intersegment sales or transfers for the year ended December 31, 2014 and December 31, 2013.
		Years ended December 31,
		2014		2013		2012
	Revenue:
	Applied Technologies	$	86,168	$	93,216	$	91,675
	On-Road Systems		37,031		55,090		37,558
	Off-Road Systems		3,789		3,309		3,149
	Corporate and Technology Investments		3,581		12,417		23,244
	CWI		337,234		310,651		198,015
	WWI		618,465		466,580		272,086
	Total segment revenues		1,086,268		941,263		625,727
	Less: equity investees' revenue		-955,699		-777,231		-470,101
	Total consolidated revenues	$	130,569	$	164,032	$	155,626
	Net consolidated operating income (loss) excluding depreciation and amortization, losses on impairments, write-downs and disposals, provision for inventory purchase commitments, foreign exchange loss (gain), bank charges and other:
	Applied Technologies	$	-5,204	$	6,635	$	9,820
	On-Road Systems		-14,431		-59,843		-40,937
	Off-Road Systems		-2,744		-14,218		-13,653
	Corporate and Technology Investments		-87,363		-83,546		-50,211
	CWI		21,555		23,539		35,368
	WWI		78,502		14,496		9,765
	Total segment operating loss		-9,685		-112,937		-49,848
	Less: equity investees’ operating income		-100,057		-38,035		-45,133
	Net consolidated operating loss excluding depreciation and amortization, losses on impairments, write-downs and disposals, provision for inventory purchase commitments, foreign exchange (gain) loss, bank charges and other:		-109,742		-150,972		-94,981
	Depreciation and amortization:
	Applied Technologies		8,012		7,838		7,905
	On-Road Systems		5,561		3,186		1,028
	Off-Road Systems		—		450		83
	Corporate and Technology Investments		5,093		4,814		2,379
	Provision for inventory purchase commitments (On-Road Systems)		4,106		—		—
	Losses on impairments, write-downs and disposals
	Corporate and Technology Investments		3,458		31,564		—
	On-Road Systems		26,146		9,959		—
			52,376		57,811		11,395
	Net consolidated operating loss before foreign exchange (gain) loss, bank charges and other		-162,118		-208,783		-106,376
	Foreign exchange (gain) loss, bank charges and other		-2,731		-14,573		1,922
	Loss from operations		-159,387		-194,210		-108,298
	Interest on long-term debt and other income (expenses), net		-5,032		-3,771		-4,928
	Income from investment accounted for by the equity method		14,222		13,444		16,190
	Loss before income taxes	$	-150,197	$	-184,537	$	-97,036
		Years ended December 31,
		2014		2013		2012
	Total additions to long-lived assets excluding business combinations:
	Applied Technologies	$	938	$	4,408	$	3,000
	On-Road Systems		1,340		15,555		10,306
	Off-Road Systems		—		908		1,481
	Corporate and Technology Investments		7,971		5,579		16,565
		$	10,249	$	26,450	$	31,352
	It is impracticable for the Company to provide geographical revenue information by individual countries; however, it is practicable to provide it by geographical regions.  Product and service and other revenues are attributable to geographical regions based on location of the Company’s customers and presented as a percentage of the Company’s product and service revenues are as follows:
		% of total product revenue and service and other revenue
		Years ended December 31,
		2014		2013		2012
	Americas (including United States)		40		42		38
	Asia (including China)		12		11		9
	Other (including Italy)		48		47		53
The Company’s revenue earned from Canadian customers is not significant and has been included in revenue from sales in the Americas.
As at December 31, 2014, total goodwill of $23,352 (December 31, 2013 - $22,958) was allocated to Applied Technologies and $nil (December 31, 2013 - $18,542) to On-Road Systems segments.
As at December 31, 2014, total long-term investments of $32,898 (December 31, 2013 - $21,872) was allocated to the Corporate segment and $426 (December 31, 2013 - $256) was allocated to Applied Technologies.
Total assets are allocated as follows:
	December 31, 2014		December 31, 2013
Applied Technologies	$	151,428	$	144,803
On-Road Systems		130,461		111,323
Off-Road Systems		1,042		6,564
Corporate and Technology Investments and unallocated assets		54,764		228,981
CWI		172,941		115,343
WWI		182,215		131,146
		692,851		738,160
Less: equity investees’ total assets		355,156		246,489
Total consolidated assets	$	337,695	$	491,671
The Company’s long-lived assets consist of property, plant and equipment, intangible assets and goodwill.
Long-lived assets information by geographic area:
	December 31, 2014		December 31, 2013
Italy	$	53,319	$	66,918
Netherlands		9,944		—
Canada		25,083		30,713
United States		20,320		47,322
Sweden		208		322
China		6,329		8,675
Australia		1,233		1,360
		116,436		155,310
Less: equity investees’ long-lived assets		7,030		8,117
Total consolidated long-lived assets	$	109,406	$	147,193

Financial_instruments

Financial instruments	12 Months Ended
	Dec. 31, 2014
Financial Instruments Disclosure [Abstract]
Financial Instruments Disclosure [Text Block]	24	Financial instruments:
	(a)	Financial risk management:
	The Company has exposure to liquidity risk, credit risk, foreign currency risk and interest rate risk.
	(b)	Liquidity risk:
	Liquidity risk is the risk that the Company will not be able to meet its financial obligations as they are due.  The Company has sustained losses and negative cash flows from operations since inception.  At December 31, 2014, the Company has $94,005 of cash, cash equivalents and short-term investments.
	The following are the contractual maturities of financial obligations as at December 31, 2014:
			Carrying		Contractual
			amount		cash flows		< 1 year		1-3 years		4-5 years		>5 years
	Accounts payable and accrued liabilities		$	55,502	$	55,502	$	55,502		$—		$—		$—
	Unsecured subordinated debentures (1)			46,491		68,613		4,950		63,663		—		—
	Senior financing (2)			15,910		16,565		6,314		8,353		779		1,120
	Senior revolving financing (3)			12,101		12,743		315		12,429		—		—
	Other bank financing (4)			2,646		3,135		1,050		478		121		1,485
	Capital lease obligations			1,394		1,490		626		665		200		—
	Operating lease commitments			—		57,867		3,946		10,868		9,929		33,125
	Royalty payments (5)			1,294		15,927		1,164		2,327		2,327		10,108
			$	135,338	$	231,842	$	73,867	$	98,783	$	13,356	$	45,838
	(1) Includes interest at 9%.
	(2) Includes interest at rates disclosed in note 13(b) in effect at December 31, 2014.
	(3) Includes interest at rates disclosed in note 13(c) in effect at December 31, 2014.
	(4) Includes interest at rates disclosed in note 13(d) in effect at December 31, 2014.
	(5) From fiscal 2011 to 2015 inclusive, the Company is obligated to pay annual royalties equal to the greater of $1,164 (CDN$1,350) or 0.33% of the Company's gross annual revenue from all sources, provided that gross revenue exceeds $12,693 (CDN$13,500) in any aforementioned fiscal year, up to a maximum of $26,514 (CDN$28,189).  The Company has assumed the minimum required payments.
	(c)	Credit risk:
	Credit risk arises from the potential that a counterparty to a financial instrument fails to meet its contractual obligations and arises principally from the Company’s cash and cash equivalents, short-term investments and accounts receivable.  The Company manages credit risk associated with cash and cash equivalents and short-term investments by regularly consulting with its current bank and investment advisors and investing primarily in liquid short-term paper issued by Schedule 1 Canadian banks, R1 rated companies and governments.  The Company monitors its portfolio, and its policy is to diversify its investments to manage this potential risk.
	The Company is also exposed to credit risk with respect to uncertainties as to timing and amount of collectability of accounts receivable and loans receivable.  As at December 31, 2014, 87% (December 31, 2013 - 88%) of accounts receivable relates to customer receivables, 1% (December 31, 2013 - 1%) relates to government grants receivable and 12% (December 31, 2013 - 11%) relates to amounts due from joint venture and indirect, income tax and value added taxes receivable.  In order to minimize the risk of loss for customer receivables, the Company’s extension of credit to customers involves review and approval by senior management as well as progress payments as contracts are executed.  Most sales are invoiced with payment terms in the range of 30 days to 90 days.  The Company reviews its customer receivable accounts and regularly recognizes an allowance for doubtful receivables as soon as the account is determined not to be fully collectible.  Estimates for allowance for doubtful debts are determined by a customer-by-customer evaluation of collectability at each balance sheet reporting date, taking into consideration past due amounts and any available relevant information on the customers’ liquidity and financial position.
	The carrying amount of cash and cash equivalents, short-term investments and accounts receivable as at December 31, 2014 of $140,854 (December 31, 2013 - $269,919) represents the Company’s maximum credit exposure.
	(d)          Foreign currency risk:
	Foreign currency risk is the risk that the fair value of future cash flows of financial instruments will fluctuate because of changes in foreign currency exchange rates.  The Company conducts a significant portion of its business activities in foreign currencies, primarily the United States dollar (“U.S.”) and the Euro (“Euro”).  Cash and cash equivalents, short-term investments, accounts receivable, accounts payable, and long-term debt that are denominated in foreign currencies will be affected by changes in the exchange rate between the Canadian dollar and these foreign currencies.
	The Company’s functional currency is the Canadian dollar. The U.S. dollar and the Euro carrying amount of financial instruments subject to exposure to foreign currency risk in the consolidated balance sheet  at December 31, 2014 is as follows:
			U.S. dollars
	Cash and cash equivalents		$	69,899
	Short-term investments			500
	Accounts receivable			14,304
	Accounts payable			4,012
				Euros
	Cash and cash equivalents		€	9,190
	Accounts receivable			38,916
	Accounts payable			27,667
	If foreign exchange rates on December 31, 2014 had changed by 25 basis points, with all other variables held constant, net loss for the year ended December 31, 2014 would have changed by $201 and $51 for US dollar denominated and Euro denominated financial instruments, respectively.  The Company’s exposure to currencies other than U.S. dollars and Euros is not material.
	(e)	Interest rate risk:
	Interest rate risk is the risk that the fair value of future cash flows of a financial instrument will fluctuate because of changes in market interest rates.  The Company is subject to interest rate risk on certain long-term debt with variable rates of interest.  The Company limits its exposure to interest rate risk by continually monitoring and adjusting portfolio duration to align to forecasted cash requirements and anticipated changes in interest rates.
	If interest rates for the year ended December 31, 2014 had increased or decreased by 50 basis points, with all other variables held constant, net loss for the year ended December 31, 2014 would have increased or decreased by $52.
	(f)	Fair value of financial instruments:
	The carrying amounts reported in the balance sheets for cash and cash equivalents, accounts receivable, accounts payable and accrued liabilities and loan payable approximate their fair values due to the short-term period to maturity of these instruments.
	The Company’s short-term investments are recorded at fair value.  The long-term investment represents our interests in the CWI, WWI and other equity accounted for investees, which are accounted for using the equity method.
	The carrying value reported in the balance sheets for obligations under capital lease, which is based upon discounted cash flows, approximates its fair value.
	The carrying value reported in the balance sheet for the unsecured subordinated debenture notes (note 13(a)) approximates its fair value, based on market rates of interest for similar indebtedness. Additionally, the interest rate on the notes approximates the interest rate being demanded in the market for debt with similar terms and conditions.
	The carrying value reported in the balance sheet for senior financing agreements (note 13(b and c)) approximates their fair values as at December 31, 2014, as the interest rates on the debt is floating and therefore approximates the market rates of interest.  The Company’s credit spread also has not substantially changed from the premiums currently paid.
	The Company categorizes its fair value measurements for items measured at fair value on a recurring basis into three categories as follows:
		Level 1 –	Unadjusted quoted prices in active markets for identical assets or liabilities.
		Level 2 –	Observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.
		Level 3 –	Inputs for the asset or liability that are not based on observable market data (unobservable inputs).
	When available, the Company uses quoted market prices to determine fair value and classify such items in Level 1.  When necessary, Level 2 valuations are performed based on quoted market prices for similar instruments in active markets and/or model–derived valuations with inputs that are observable in active markets.  Level 3 valuations are undertaken in the absence of reliable Level 1 or Level 2 information.
	As at December 31, 2014, cash and cash equivalents and short-term investments are measured at fair value on a recurring basis and are included in Level 1.

Subsequent_Events

Subsequent Events	12 Months Ended
	Dec. 31, 2014
Subsequent Events [Abstract]
Subsequent Events [Text Block]	25.           Subsequent Events
	Other than the shares issued in connection with the earn-out payments as described in note 15b there were no subsequent events that occurred after the balance sheet date through March 9, 2015, the date when the financial statements were issued.

Significant_accounting_policie1

Significant accounting policies (Policies)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Basis of Accounting, Policy [Policy Text Block]	(a)	Basis of presentation:
	The consolidated financial statements include the accounts of the Company, its wholly owned subsidiaries and variable interest entities (“VIEs”) for which the Company is considered the primary beneficiary.  All intercompany balances and transactions have been eliminated on consolidation.
	These consolidated financial statements are presented in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”).
	The Company has sustained net losses over the past several years and as at December 31, 2014 have an accumulated a deficit of $765.0 million. As at December 31, 2014 the Company has cash and cash equivalents of $93.3 million. The Company’s ability to continue as a going concern is dependent on its available cash, its ability to find new sources of financing or raise cash through the sale of assets while in pursuit of operating profitability. Over the past year, the Company has taken immediate actions to right-size the business structure and reduce expenses through activities including staff reductions and deferral of non-core development programs.  Management believes these factors will contribute toward achieving profitability, though further expense reductions may be required. However, there can be no assurance that the Company will be successful in achieving its objectives. Management believes that the cash balances available as of December 31, 2014, combined with cost cutting measures in place and its ability to find new sources of financing or raise cash through the sale of assets subsequent to the balance sheet date, provides sufficient funds for the Company to meet its obligations beyond the next 12 months. The accompanying financial statements do not include any adjustments that might be necessary if the Company is unable to continue as a going concern.
Foreign Currency Transactions and Translations Policy [Policy Text Block]	(b)	Foreign currency translation:
	The Company’s reporting currency for its consolidated financial statement presentation is the United States dollar.  The functional currencies of the Company’s operations and subsidiaries include the following: United States, Canadian and Australian dollar, Euro, Chinese Renminbi (“RMB”), and Swedish Krona.  The Company translates assets and liabilities of non-US dollar functional currency operations using the period end exchange rates,  shareholders’ equity balances using the weighted average of historical exchange rates, and revenues and expenses using the monthly average rate for the period with the resulting exchange differences recognized in other comprehensive income.
	Transactions that are denominated in currencies other than the functional currency of the Company’s operations or its subsidiaries are translated at the rate in effect on the date of the transaction.  Foreign currency denominated monetary assets and liabilities are translated to the applicable functional currency at the exchange rate in effect on the balance sheet date.  Non-monetary assets and liabilities are translated at the historical exchange rate.  All foreign exchange gains and losses are recognized in the statement of operations, except for the translation gains and losses arising from available-for-sale instruments, which are recorded through other comprehensive income until realized through disposal or impairment.
	Except as otherwise noted, all amounts in these financial statements are presented in U.S. dollars.  For the periods presented, the Company used the following exchange rates:
			Period end exchange rate as at:					Average for the year ended:
			December 31, 2014			December 31, 2013		December 31, 2014		December 31, 2013
	Canadian dollar			0.86			0.94		0.91		0.97
	Australian dollar			0.82			0.89		0.9		0.97
	Euro			1.21			1.38		1.33		1.33
	RMB			0.16			0.17		0.16		0.16
	Swedish Krona			0.13			0.16		0.15		0.15
Cash and Cash Equivalents, Policy [Policy Text Block]	(c)	Cash and cash equivalents:
	Cash and cash equivalents includes cash, term deposits, bankers acceptances and guaranteed investment certificates with maturities of ninety days or less when acquired.  Cash equivalents are considered as held for trading and recorded at fair value with changes in fair value recognized in the consolidated statements of operations.
Short Term Investments [Policy Text Block]	(d)	Short-term investments:
	Short-term investments, consisting of investment grade commercial paper, banker acceptances, bearer deposit notes, guaranteed investment certificates and other term deposits, are considered available for sale and recorded at fair value with changes in fair value recognized in accumulated other comprehensive income until realized.  A decline in value that is considered other than temporary is recognized in net loss for the period.
Receivables, Policy [Policy Text Block]	(e)	Accounts receivable, net:
	Accounts receivable are measured at amortized cost.  The Company maintains allowances for doubtful accounts for estimated losses resulting from the inability of its customers to make required payments. Management considers the following factors when determining the collectibility of specific customer accounts: customer credit-worthiness, past transaction history with the customer, current economic industry trends, and changes in customer payment terms. Past due balances over 90 days and other higher risk amounts are reviewed individually for collectibility. If the financial condition of the Company’s customers were to deteriorate, adversely affecting their ability to make payments, additional allowances would be required. Based on management’s assessment, the Company provides for estimated uncollectible amounts through a charge to earnings and a credit to a valuation allowance. Balances that remain outstanding after the Company has used reasonable collection efforts are written off through a charge to the valuation allowance and a credit to accounts receivable.
Inventory, Policy [Policy Text Block]	(f)	Inventories:
	The Company’s inventories consist of the Company’s fuel system products (finished goods), work-in-progress, purchased parts and assembled parts. Inventories are recorded at the lower of cost and net realizable value.  Cost is determined based on the lower of weighted average cost and net realizable value.  The cost of fuel system product inventories, assembled parts and work-in-progress includes materials, labour and production overhead including depreciation. The Company provides inventory write-downs based on excess and obsolete inventories determined primarily by future demand forecasts. In addition, the Company records a liability for firm, noncancelable, and unconditional purchase commitments with manufacturers for quantities in excess of the Company’s future demand forecast consistent with its valuation of excess and obsolete inventory.
Property, Plant and Equipment, Policy [Policy Text Block]	(g)	Property, plant and equipment:
	Property, plant and equipment are stated at cost.  Depreciation is provided as follows:
	Assets		Basis		Rate
	Buildings		Straight-line		15 years
	Computer equipment and software		Straight-line		3 years
	Furniture and fixtures		Straight-line		5 years
	Machinery and equipment		Straight-line		8 – 10 years
	Leasehold improvements		Straight-line		Lease term
Long Term Investments [Policy Text Block]	(h)	Long-term investments:
	The Company accounts for investments in which it has significant influence, including VIEs for which the Company is not the primary beneficiary, using the equity basis of accounting.  Under the equity method, the Company recognizes its share of income from equity accounted investees in the statement of operations with a corresponding increase in long-term investments.  Any dividends paid or payable are credited against long-term investments.
Financial Liabilities [Policy Text Block]	(i)	Financial liabilities:
	Accounts payable and accrued liabilities, short-term debt and long-term debt are measured at amortized cost.  Transaction costs relating to long-term debt are deferred in other assets on initial recognition and are amortized using the effective interest rate method.
Research and Development Expense, Policy [Policy Text Block]	(j)	Research and development costs:
	Research and development costs are expensed as incurred and are recorded net of government funding received or receivable.
Government Assistance [Policy Text Block]	(k)	Government assistance:
	The Company periodically applies for financial assistance under available government incentive programs, which is recorded in the period it is received or receivable.  Government assistance relating to the purchase of property, plant and equipment is reflected as a reduction of the cost of such assets.  Government assistance related to research and development activities is recorded as a reduction of the related expenditures.
Goodwill and Intangible Assets, Intangible Assets, Policy [Policy Text Block]	(l)	Intangible assets:
	Intangible assets consist primarily of the cost of intellectual property, trademarks, technology, customer contracts and non-compete agreements.  Intangible assets are amortized over their estimated useful lives, which range from 5 to 20 years.
Asset Retirement Obligations, Policy [Policy Text Block]	(m)	Impairment of long-lived assets:
	The Company reviews its long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of the assets may not be recoverable.  If such conditions exist, assets are considered impaired if the sum of the undiscounted expected future cash flows expected to result from the use and eventual disposition of an asset is less than its carrying amount.  An impairment loss is measured at the amount by which the carrying amount of the asset exceeds its fair value.  When quoted market prices are not available, the Company uses the expected future cash flows discounted at a rate commensurate with the risks associated with the recovery of the asset as an estimate of fair value.
Goodwill and Intangible Assets, Policy [Policy Text Block]	(n)	Goodwill impairment:
	Goodwill is recorded at the time of purchase for the excess of the amount of the purchase price over the fair values of the identifiable assets acquired and liabilities assumed.  Goodwill is not amortized and instead is tested at least annually for impairment, or more frequently when events or changes in circumstances indicate that goodwill might be impaired.  This impairment test is performed annually at November 30.  Future adverse changes in market conditions or poor operating results of underlying assets could result in an inability to recover the carrying value of the goodwill, thereby possibly requiring an impairment charge.
	A two-step test is used to identify a potential impairment and to measure the amount of impairment, if any.  The first step is to compare the fair value of the reporting unit with its carrying amount, including goodwill.  If the fair value of the reporting unit exceeds its carrying amount, goodwill is considered not impaired; otherwise, goodwill is impaired and the loss is measured by performing step two.  Under step two, the impairment loss is measured by comparing the implied fair value of the reporting unit goodwill with the carrying amount of goodwill.
	Fair value is determined using widely accepted valuation techniques, which may include discounted cash flows and market multiple analyses.  These types of analyses contain uncertainties because they require management to make assumptions and to apply judgment to estimate industry economic factors and the profitability of future business strategies.
Standard Product Warranty, Policy [Policy Text Block]	(o)	Warranty liability:
	Estimated warranty costs are recognized at the time the Company sells its products and are included in cost of revenue.  The Company provides warranty coverage on products sold for a period ending two years from the date the products are put into service by customers.  Warranty liability represents the Company’s best estimate of warranty costs expected to be incurred during the warranty period.  Furthermore, the current portion of warranty liability represents the Company’s best estimate of the costs to be incurred in the next twelve-month period.  The Company uses historical failure rates and cost to repair defective products to estimate the warranty liability.  New product launches require a greater use of judgment in developing estimates until claims experience becomes available.  Product specific experience is typically available four or five quarters after product launch, with a clear experience trend not evident until eight to twelve quarters after launch.  The Company records warranty expense for new products upon shipment using a factor based upon historical experience from previous engine generations in the first year, a blend of actual product and historical experience in the second year and product specific experience thereafter.  The amount payable by the Company and the timing will depend on actual failure rates and cost to repair failures of its products.  Since a number of the Company’s products are new in the market, historical data may not necessarily reflect actual costs to be incurred and may result in significant fluctuations in the warranty liability.
Extended Product Warranty, Policy [Policy Text Block]		(p)	Extended warranty:
	The Company sells extended warranty contracts that provide coverage in addition to the basic warranty coverage.  Proceeds from the sale of these contracts are deferred and amortized over the extended warranty period commencing at the end of the basic warranty period.  On a periodic basis, management reviews the estimated costs expected to be incurred related to servicing these contracts and recognizes a loss to the extent such costs exceed the related deferred revenue. Extended warranty costs are expensed as period costs as incurred.
Revenue Recognition, Policy [Policy Text Block]		(q)	Revenue recognition:
	Product revenue
	The Company’s primary source of revenue is from the sale of kits, Westport LNG systems and parts, and Westport CNG and LPG fuel systems for OEMs in the light-duty automotive and industrial markets.  Product revenue is recognized when contractual terms are agreed upon, the price is fixed or determinable, the products are shipped and title passes to the customer and collectability is reasonably assured.
	Revenue from research and development
	The Company also earns service revenue from research and development arrangements under which the Company provides contract services relating to developing natural gas engines or biogas engines for use in products and providing ongoing development services to assist with the development and commercialization of products.  These contracts provide for the payment for services based on our achieving defined milestones or on the performance of work under product development programs.  Revenues are recognized using the milestone method based on assessment of progress achieved against the defined milestones.  Revenue may also be recognized using the proportionate performance method of accounting based on the performance of work under the research and development arrangement.  There is a risk that a customer may ultimately disagree with our assessment of the progress achieved against milestones or that our estimates of the percentage of work completed could change. Should this occur, the revenues recognized in the period might require adjustment in a subsequent period. All costs incurred related to revenue earned from research and development arrangements are recorded as research and development expense as incurred.
	Revenue from contracts
	The Company earns revenue under certain contracts to provide engineering development services.  These contracts provide for the payment for services based on the performance of work under product development programs.  Revenues are recognized under these contracts based on the percentage of completion method of accounting.  The components to measure percentage of completion are complex and subject to many variables.  Components may include estimated costs to complete a contract, estimated hours to completion or management’s assessment of work to be performed.  When estimates of total costs to be incurred on a contract exceed total estimates of revenue to be earned, a provision for the entire loss on the contract is recorded in the period the loss is determined.  There is a risk that the estimated percentage of completion of a contract may change, which may result in an adjustment to previously recognized revenues. All costs incurred related to revenue earned from contracts are recorded in cost of products sold.
	Arrangements with customers may include multiple deliverables, including any combination of products, services, and licenses. In these arrangements, the Company allocates revenue to all deliverables based on their relative selling prices. The Company uses a hierarchy to determine the selling price to be used for allocating revenue to deliverables: (a) vendor-specific objective evidence of fair value (VSOE), (b) third-party evidence of selling price (TPE), and (c) best estimate of selling price (BESP), which are determined as follows:
	VSOE-In limited circumstances are products sold separately in stand-alone arrangements.  In determining VSOE, the Company requires that a substantial majority of the selling prices for a product or service falls within a reasonably narrow pricing range, generally evidenced by the pricing rates of approximately 85% of such historical stand-alone transactions falling within plus or minus 10% of the median rate. In addition, the Company considers the geographies in which the products or services are sold, major product and service groups, customer classification, and other environmental or marketing variables in determining VSOE.
	TPE-VSOE exists only when the Company sells the deliverable separately. When VSOE does not exist, the Company attempts to determine TPE based on competitor prices for similar deliverables when sold separately. Generally, the Company’s go-to-market strategy for many of its products differs from that of its peers and its offerings contain a significant level of customization and differentiation such that the comparable pricing of products with similar functionality sold by other companies cannot be obtained. Furthermore, the Company is unable to reliably determine what similar competitor products’ selling prices are on a stand-alone basis. Therefore, the Company is typically not able to determine TPE.
	BESP-The objective of BESP is to determine the price at which the Company would transact a sale if the product or service were sold on a stand-alone basis. When both VSOE and TPE do not exist, the Company determines BESP by first collecting all reasonably available data points including sales, cost and margin analysis of the product, and other inputs based on the Company’s normal pricing practices. Second, the Company makes any reasonably required adjustments to the data based on market and Company-specific factors. Third, the Company stratifies the data points, when appropriate, based on customer, magnitude of the transaction and sales volume.
	Once elements of an arrangement are separated into more than one unit of accounting, revenue is recognized for each separate unit of accounting based on the nature of the revenue as described above.
	Changes in cost estimates and the fair values of certain deliverables could negatively impact the Company’s operating results. In addition, unforeseen conditions could arise over the contract term that may have a significant impact on the Company’s operating results.
	License revenue
	Revenue from technology license fees is recognized over the duration of the licensing agreement.  Amounts received in advance of the revenue recognition criteria being met are recorded as deferred revenue.
Income Tax, Policy [Policy Text Block]	(r)	Income taxes:
	The Company accounts for income taxes using the asset and liability method.  Under this method, deferred income tax assets and liabilities are determined based on the temporary differences between the accounting basis and tax basis of the assets and liabilities and for loss carry-forwards, tax credits and other tax attributes, using the enacted tax rates in effect for the years in which the differences are expected to reverse.  The effect of a change in tax rates on the deferred income tax assets and liabilities is recognized in income in the period that includes the enactment date.
	The Company recognizes deferred income tax assets to the extent the assets are more-likely-than-not to be realized. In making such a determination the Company considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies, and results of recent operations. If it is determined that, based on all available evidence, it is more-likely-than-not that some or all of the deferred income tax assets will not be realized, a valuation allowance is provided to reduce the deferred income tax assets.
	The Company uses a two-step process to recognize and measure the income tax benefit of uncertain tax positions taken or expected to be taken in a tax return. The tax benefit from an uncertain tax position is recognized if it is more-likely-than-not that the position will be sustained upon examination by a tax authority based solely on the technical merits of the position. A tax benefit that meets the more-likely-than-not recognition threshold is measured as the largest amount that is greater than 50% likely to be realized upon settlement with the tax authority. To the extent a full benefit is not expected to be realized, an income tax liability is established. Any change in judgment related to the expected resolution of an uncertain tax position is recognized in the year of such a change.

Significant_accounting_policie2

Significant accounting policies (Tables)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Schedule Of Foreign Currency Exchange Rate Translation [Table Text Block]	For the periods presented, the Company used the following exchange rates:
		Period end exchange rate as at:					Average for the year ended:
		December 31, 2014			December 31, 2013		December 31, 2014		December 31, 2013
	Canadian dollar		0.86			0.94		0.91		0.97
	Australian dollar		0.82			0.89		0.9		0.97
	Euro		1.21			1.38		1.33		1.33
	RMB		0.16			0.17		0.16		0.16
	Swedish Krona		0.13			0.16		0.15		0.15
Schedule of Property Plant and Equipment Components [Table Text Block]	Property, plant and equipment are stated at cost.  Depreciation is provided as follows:
	Assets	Basis		Rate
	Buildings	Straight-line		15 years
	Computer equipment and software	Straight-line		3 years
	Furniture and fixtures	Straight-line		5 years
	Machinery and equipment	Straight-line		8 – 10 years
	Leasehold improvements	Straight-line		Lease term

Business_Combinations_Tables

Business Combinations (Tables)	12 Months Ended
	Dec. 31, 2014
Prins Autogassystemen Holding B.V. [Member]
Schedule Of Purchase Price Allocations [Table Text Block]	The estimated fair values of assets acquired and liabilities assumed are provisional and are based on the information that was available as of the acquisition date to estimate the fair value of assets acquired and liabilities assumed. The Company believes that information provides a reasonable basis for estimating the fair values of assets acquired and liabilities assumed, but the Company is waiting for additional information necessary to finalize those fair values. Therefore, the provisional measurements of fair value reflected are subject to change and such changes could be significant. The Company expects to finalize the valuation and complete the purchase price allocation as soon as practicable but no later than one year from the acquisition date.
	Consideration allocated to:
	Other tangible assets, including cash of $61	$	13,138
	Property, plant and equipment		3,824
	Intangible assets subject to amortization over 5 years		3,024
	Goodwill		3,221
	Total assets acquired	$	23,207
	Less:
	Current liabilities		7,211
	Deferred income tax liabilities		979
	Debt assumed (note 13b and c)		11,905
		$	20,095
	Total net assets acquired	$	3,112
	Consideration:
	Paid to sellers	$	3,112
Business Acquisition, Pro Forma Information [Table Text Block]	This supplemental pro forma information has been prepared for comparative purposes and does not purport to be indicative of what would have occurred had the acquisition been made on January 1, 2013, nor are they indicative of any future results.
		Years ended December 31,
		2014		2013
	Revenue
	Revenue for the period	$	130,569	$	164,032
	Add: BAF - see (note 4(b))		—		7,249
	Add: Prins		30,993		30,885
	Pro forma revenue for the period	$	161,562	$	202,166
	Net Loss
	Net loss for the period	$	-149,618	$	-185,410
	Add: BAF - see (note 4(b))		—		-4,038
	Add: Prins		91		9,164
	Pro forma net loss for the period	$	-149,527	$	-180,284
BAF Technologies Inc [Member]
Schedule Of Purchase Price Allocations [Table Text Block]	The following table summarizes management’s final fair market valuation of the assets acquired and liabilities assumed at the acquisition date based on the results of a valuation report issued by a third-party valuation firm.
	Consideration allocated to:
	Other tangible assets, including cash of $1,178	$	9,116
	Property, plant and equipment		905
	Intangible assets subject to amortization over 3 to 10 years		7,729
	Goodwill		18,542
	Total assets acquired		36,292
	Less: total liabilities		-6,594
	Total net assets acquired	$	29,698
	Consideration:
	Payable to Clean Energy	$	2,322
	Common shares issued		24,091
	Common shares to be issued		3,285
		$	29,698
Schedule of Acquired Finite-Lived Intangible Assets by Major Class [Table Text Block]	The fair values for specifically identifiable intangible assets by major asset class are as set forth below.
				Weighted average
		Assigned fair value		amortization period
	Customer relationships	$	6,350		8 years
	Core technology		160		10 years
	Other intangibles		1,219		3 years
	Total	$	7,729		7 years
Business Acquisition, Pro Forma Information [Table Text Block]	The following unaudited supplemental pro forma information presents the consolidated financial results as if the acquisition of BAF had occurred on January 1, 2012.  This supplemental pro forma information has been prepared for comparative purposes and does not purport to be indicative of what would have occurred had the acquisition been made on January 1, 2012, nor are they indicative of any future results.
		Years ended December 31,
		2013		2012
	Revenue	$	171,281	$	181,972
	Net loss	$	-189,448	$	-100,946

Accounts_Receivable_Tables

Accounts Receivable (Tables)	12 Months Ended
	Dec. 31, 2014
Receivables [Abstract]
Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block]		December 31, 2014		December 31, 2013
	Customer trade receivable	$	43,256	$	54,017
	Government funding receivable		38		483
	Due from joint venture (note 20)		2,538		3,621
	Other receivables		3,269		2,689
	Income tax receivable		499		77
	Allowance for doubtful accounts		-2,751		-1,572
		$	46,849	$	59,315

Inventories_Tables

Inventories (Tables)	12 Months Ended
	Dec. 31, 2014
Inventory Disclosure [Abstract]
Schedule of Inventory, Current [Table Text Block]		December 31, 2014		December 31, 2013
	Purchased parts	$	28,227	$	23,228
	Work-in-process		4,879		10,770
	Finished goods		8,718		6,628
		$	41,824	$	40,626

Longterm_investments_Tables

Long-term investments (Tables)	12 Months Ended
	Dec. 31, 2014
Long Term Investment [Table Text Block]		December 31, 2014		December 31, 2013
	Weichai Westport Inc. (a)	$	18,791	$	14,534
	Cummins Westport Inc. (b)		13,196		7,191
	Other equity accounted for investees		1,337		403
		$	33,324	$	22,128
Weichai Westport Inc. [Member]
Schedule of Equity Method Investments [Table Text Block]	Assets, liabilities, revenue and expenses of WWI as of and for the periods presented are as follows:
		December 31,		December 31,
		2014		2013
	Current assets:
	Cash and short-term investments	$	11,734	$	4,696
	Accounts receivable		72,121		31,967
	Inventory		83,594		80,412
	Other current assets		1,249		176
	Long-term assets
	Property, plant and equipment		5,736		7,021
	Deferred income tax assets		7,781		6,874
	Total assets	$	182,215	$	131,146
	Current liabilities:
	Accounts payable and accrued liabilities	$	128,838	$	93,016
	Total liabilities	$	128,838	$	93,016
		Years ended December 31,
		2014		2013		2012
	Product revenue	$	618,465	$	466,580	$	272,086
	Cost of revenue and expenses:
	Cost of product revenue		565,943		429,238		247,299
	Operating expenses		32,227		22,846		15,022
			598,170		452,084		262,321
	Income before income taxes		20,295		14,496		9,765
	Income tax expense		3,076		2,315		1,536
	Income for the period	$	17,219	$	12,181	$	8,229
Cummins Westport, Inc. [Member]
Schedule of Equity Method Investments [Table Text Block]	Assets, liabilities, revenue and expenses of CWI are as follows:
		December 31, 2014		December 31, 2013
	Current assets:
	Cash and short-term investments	$	107,415	$	73,736
	Accounts receivable		12,741		4,645
	Current portion of deferred income tax assets		21,967		13,958
	Other current assets		116		210
	Long-term assets:
	Property, plant and equipment		1,294		1,096
	Deferred income tax assets		29,408		21,698
	Total assets	$	172,941	$	115,343
	Current liabilities:
	Current portion of warranty liability	$	48,818	$	18,395
	Current portion of deferred revenue		8,029		5,478
	Accounts payable and accrued liabilities		6,419		7,772
			63,266		31,645
	Long-term liabilities:
	Warranty liability		43,983		49,174
	Deferred revenue		34,345		17,815
	Other long-term liabilities		2,771		2,400
			81,099		69,389
	Total liabilities	$	144,365	$	101,034
		Years ended December 31,
		2014		2013		2012
	Product revenue	$	283,551	$	261,012	$	161,741
	Parts revenue		53,683		49,639		36,274
			337,234		310,651		198,015
	Cost of revenue and expenses:
	Cost of product and parts revenue		270,832		246,403		136,575
	Research and development		21,131		21,522		12,114
	General and administrative		1,202		1,348		1,417
	Sales and marketing		22,514		17,839		12,541
	Foreign exchange (gain) loss		34		-7		-18
	Bank charges, interest and other		805		607		472
			316,518		287,712		163,101
	Income from operations		20,716		22,939		34,914
	Interest and investment income		260		117		530
	Income before income taxes		20,976		23,056		35,444
	Income tax expense (recovery):
	Current		21,514		24,600		16,362
	Deferred		-15,719		-18,566		-6,517
			5,795		6,034		9,845
	Income for the period	$	15,181	$	17,022	$	25,599

Variable_interest_entities_Tab

Variable interest entities (Tables)	12 Months Ended
	Dec. 31, 2014
Variable Interest Entities [Abstract]
Schedule of Variable Interest Entities [Table Text Block]	The carrying amount and maximum exposure to losses relating to VIEs in which the Company holds a significant variable interest but is not the primary beneficiary, and which have not been consolidated, were as follows:
		Balance at December 31, 2014				Balance at December 31, 2013
		Carrying		Maximum		Carrying		Maximum
		amount		exposure to		amount		exposure
				loss				to loss
	Equity method investment	$	13,196	$	13,196	$	7,191	$	7,191
	Accounts receivable		2,538		2,538		3,621		3,621

Property_plant_and_equipment_T

Property, plant and equipment (Tables)	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment [Table Text Block]				Accumulated		Net book
	December 31, 2014	Cost		depreciation		value
	Land and buildings	$	3,015	$	—	$	3,015
	Computer equipment and software		9,277		7,063		2,214
	Furniture and fixtures		6,194		1,798		4,396
	Machinery and equipment		81,933		36,135		45,798
	Leasehold improvements		12,460		9,749		2,711
		$	112,879	$	54,745	$	58,134
				Accumulated		Net book
	December 31, 2013	Cost		depreciation		value
	Computer equipment and software	$	9,652	$	6,174	$	3,478
	Furniture and fixtures		6,608		1,692		4,916
	Machinery and equipment		86,067		32,099		53,968
	Leasehold improvements		15,084		10,097		4,987
		$	117,411	$	50,062	$	67,349

Intangible_assets_Tables

Intangible assets (Tables)	12 Months Ended
	Dec. 31, 2014
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Schedule of Finite-Lived Intangible Assets [Table Text Block]
				Accumulated		Net book
	December 31, 2014	Cost		amortization		value
	Patents and trademarks	$	18,425	$	3,445	$	14,980
	Technology (1)		6,449		3,142		3,307
	Customer contracts (1)		13,762		4,163		9,599
	Other intangibles (1)		62		28		34
	Total	$	38,698	$	10,778	$	27,920
				Accumulated		Net book
	December 31, 2013	Cost		amortization		value
	Patents and trademarks	$	20,974	$	2,900	$	18,074
	Technology		7,468		2,796		4,672
	Customer contracts (2)		18,447		3,886		14,561
	Other intangibles		1,262		225		1,037
	Total	$	48,151	$	9,807	$	38,344
	(1) The Company reviews its long-lived assets for impairment including property, plant and equipment, and intangible assets whenever events and changes in circumstances indicate that the carrying amount of the assets may not be recoverable. Based on the revenue and operating results and decline in the oil price, the Company concluded there were impairment indicators requiring the performance of a long-lived assets impairment test for customer contracts, technology and other intangibles as of November 30, 2014. Accordingly non-cash impairment charges aggregating to $5,823 were recorded during the year ended December 31, 2014 which reduced the carrying values of technology by $115, customer contracts by $4,705 and other intangibles by $1,003 for the On-Road Systems segment.
	(2) During the year ended December 31, 2013, there was a significant decline in revenue from the lower than expected adoption rate of natural gas vehicles in our customer contracts.  An impairment analysis of the intangibles balance indicated that the carrying value exceeded the fair value of customer contracts.  Accordingly, an intangible impairment charge of $1,721 related to customer contracts in Sweden was recognized in the On-Road Systems segment.  The fair value of customer contracts was determined using the present value of expected cash flows discounted at a rate equivalent to a market participant’s weighted-average cost of capital.

Goodwill_Tables

Goodwill (Tables)	12 Months Ended
	Dec. 31, 2014
Goodwill Disclosure [Abstract]
Schedule of Goodwill [Table Text Block]	A continuity of goodwill is as follows:
		December 31, 2014		December 31, 2013
	Balance, beginning of period:	$	41,500	$	56,879
	Acquisition of Prins (note 4(a))		3,221		—
	Acquisition of BAF (note 4(b))		—		18,542
	Impairment losses		-18,543		-34,964
	Impact of foreign exchange changes		-2,826		1,043
	Balance, end of period	$	23,352	$	41,500

Accounts_payable_and_accrued_l1

Accounts payable and accrued liabilities (Tables)	12 Months Ended
	Dec. 31, 2014
Accounts Payable and Accrued Liabilities, Current [Abstract]
Schedule of Accounts Payable and Accrued Liabilities [Table Text Block]		December 31, 2014		December 31, 2013
	Trade accounts payable	$	41,796	$	42,872
	Accrued payroll		5,270		7,937
	Accrued interest		1,237		893
	Income taxes payable		580		709
	Other payables (note 22b)		6,619		2,381
		$	55,502	$	54,792

Longterm_debt_Tables

Long-term debt (Tables)	12 Months Ended
	Dec. 31, 2014
Schedule of Long-term Debt Instruments [Table Text Block]		December 31, 2014		December 31, 2013
	Subordinated debenture notes (a)	$	46,491	$	33,847
	Senior financing (b)		15,910		15,941
	Senior revolving financing (c)		12,101		13,779
	Other bank financing (d)		2,646		403
	Capital lease obligations (e)		1,394		2,043
			78,542		66,013
	Current portion		-18,955		-53,025
		$	59,587	$	12,988
	(a)         On September 23, 2011, the Company raised $33,720 (CDN$36,000) through the issuance of debentures to Macquarie Private Wealth Inc. (“Macquarie”) on a private placement basis (the “Initial Debentures”). The Initial Debentures were unsecured and subordinated to senior indebtedness, matured on September 22, 2014, and bore interest at 9% per annum, payable in cash semi-annually in arrears on March 15 and September 15 of each year during the term, which commenced on March 15, 2012. The Initial Debentures were redeemable at the option of the Company at a price equal to $1,150 per $1,000 principal amount of the debentures on or before March 22, 2013. After March 22, 2013 and before maturity, the debentures were redeemedable at a price equal to $1,100 per $1,000 principal amount.
	On June 27, 2014, the Company raised $17,797 (CDN$19,000) through the issuance of debentures to Richardson GMP Limited (“RGMP”), formerly Macquarie Private Wealth Inc. on a private placement basis (the “Additional Debentures”). In conjunction with the issuance of the Additional Debentures, the Company amended the terms of the Initial Debentures (the “Amended Initial Debentures”). The Amended Initial Debentures are ranked pari passu with the Additional Debentures and both shall be treated as the same series of debentures (the “New Debentures”) with the same terms.  The New Debentures totaling  $51,517 (CDN$55,000) are composed of the Additional Debentures $17,797 (CDN$19,000) and the Amended Initial Debentures $33,720 (CDN$36,000). The New Debentures are unsecured and subordinated to senior indebtedness, mature on September 15, 2017, and bear interest at 9% per annum, payable in cash semi-annually in arrears on March 15 and September 15 of each year during the term. The New Debentures are redeemable at the option of the Company at a price equal to $1,150 per $1,000 principal amount of the debentures after September 15, 2015 and on or before March 15, 2016. After March 15, 2016 and before maturity, the debentures can be redeemed at a price equal to $1,100 per $1,000 principal amount.
	The New Debentures contain an extension option that will allow each debenture holder to have the option to extend, a maximum of six times, the maturity date for an additional period of six months provided that greater than CDN$10,000 of the aggregate principal amount of the New Debentures remain outstanding.
	The Company has performed the assessment of embedded derivatives within the New Debentures and concluded that there is an embedded derivative that requires bifurcation related to the extension option from the New Debentures. The extension option was deemed not clearly and closely related to the New Debentures and is separately accounted for as a standalone derivative. The Company recorded this embedded derivative as a non-current liability on its consolidated balance sheet. At issuance on June 27, 2014, the embedded derivative’s fair value was determined to be $1,169 (CDN$1,249),  which was recorded as a reduction to the carrying value of the New Debentures. The Company is accreting the carrying value of the debt to interest expense by using the effective interest method through to the maturity date of the New Debentures. The Company accreted $82 of the embedded derivative discount for the year ended December 31, 2014 (2013 $Nil ). The embedded derivative is subsequently adjusted to fair value at each reporting date, with the associated fair value loss (gain) recorded in interest and other income (loss). The fair value adjustment recorded  for the year ended December 31, 2014 was $(1,082) (2013 $Nil). The derivative liability is included in other long term liabilities on the consolidated balance sheets. The Company determined the fair value of the embedded derivative using the Interest Rate Option Pricing Method which incorporated the Black-Karasinski model.
	(b)
		December 31, 2014		December 31, 2013
	Emer Senior Financing (1)	$	9,376	$	15,941
	Prins Senior Financing (2)		3,630		—
	Prins Senior Mortgage Loan (3)		2,904		—
		$	15,910	$	15,941
	(1)         The Emer S.p.A (“Emer”) senior financing agreement bears interest at the 6-month Euribor plus  2.5% (2.7% as at December 31, 2014) and  is recorded at amortized cost using the effective interest rate method. Interest is paid semi-annually. The Company has pledged its interest in Emer as a general guarantee for its senior financing. The senior financing matures in 2017.
	(2)         A total of $7,521 Prins senior financing was assumed on the acquisition of Prins (note 4a). Principal of $3,891 was repaid on December 2, 2014. The senior financing agreement bears interest at the 3-month Euribor plus 3.5% (3.6% as at December 31, 2014). Interest is paid quarterly. The Company has pledged its interest in Prins as a general guarantee for its senior financing. The senior financing matures in 2016.
	(3)         The Prins senior mortgage loan was assumed on the acquisition of Prins (note 4a). The senior mortgage loan bears interest at 3-month Euribor plus 1% (1.1% as at December 31, 2014). Interest is paid quarterly. The Company has pledged its interest in Prins's building as a general guarantee for its senior mortgage loan. The senior mortgage loan matures in 2020.
	The principal repayment schedule of the senior financings are as follows for the years ended December 31:
		Emer Senior		Prins Senior		Prins Senior
		Financing		Financing		Mortgage Loan		Total
	2015	$	4,020	$	1,633	$	363	$	6,016
	2016		4,239		1,997		363		6,599
	2017		1,117		—		363		1,480
	2018		—		—		363		363
	2019 and thereafter		—		—		1,452		1,452
		$	9,376	$	3,630	$	2,904	$	15,910
	(c)         The senior revolving financing facility bears interest at the 6-month Euribor plus  2.5% (2.6% as at December 31, 2014) and will be repaid through two principal payments of $6,050 (€5,000) on March 31, 2016 and October 2, 2017. Interest is paid semi-annually. The Company has pledged its interest in Emer as a general guarantee for its senior revolving financing.
	Throughout the entire term of these financing arrangements, the Company is required to meet certain financial and non-financial covenants.  As of December 31, 2014, the Company is in compliance with all covenants under the financing arrangements.
	(d)
		December 31, 2014		December 31, 2013
	Emer other financing (1)	$	1,129	$	247
	Prins other financing (2)		1,424		—
	Other financing		93		156
		$	2,646	$	403
	(1)          Emer other financing consists of various unsecured bank financing arrangements that carry rates of interest ranging from 1.01% to  2.90% (2013 - 1.01% to 8.00%) and are payable on maturity dates ranging from June 23, 2015 to June 23, 2017.
	(2)         Prins other bank financing consists of a credit facility for maximum borrowings of €2,000. The credit facility bears interest at the 3 month Euribor + 3.5% (3.6% as of December 31, 2014). The credit facility is governed by an accounts receivable list requirement limiting such borrowings to 60% of accepted accounts receivable.
	(e)         The Company has capital lease obligations that have initial terms of three to five years at interest rates ranging from 3.07% to 4.93% (2013 - 3.07% to 7.32%).  The capital lease obligations require the following minimum annual principal payments during the respective fiscal years:
	2015	$	522
	2016		328
	2017		327
	2018		191
	2019		26
		$	1,394
Schedule of Maturities of Long-term Debt [Table Text Block]	The principal repayment schedule of the senior financings are as follows for the years ended December 31:
		Emer Senior		Prins Senior		Prins Senior
		Financing		Financing		Mortgage Loan		Total
	2015	$	4,020	$	1,633	$	363	$	6,016
	2016		4,239		1,997		363		6,599
	2017		1,117		—		363		1,480
	2018		—		—		363		363
	2019 and thereafter		—		—		1,452		1,452
		$	9,376	$	3,630	$	2,904	$	15,910
Schedule of Future Minimum Lease Payments for Capital Leases [Table Text Block]	The capital lease obligations require the following minimum annual principal payments during the respective fiscal years:
	2015	$	522
	2016		328
	2017		327
	2018		191
	2019		26
		$	1,394
Senior Financing [Member]
Schedule of Long-term Debt Instruments [Table Text Block]		December 31, 2014		December 31, 2013
	Emer Senior Financing (1)	$	9,376	$	15,941
	Prins Senior Financing (2)		3,630		—
	Prins Senior Mortgage Loan (3)		2,904		—
		$	15,910	$	15,941
	(1)         The Emer S.p.A (“Emer”) senior financing agreement bears interest at the 6-month Euribor plus  2.5% (2.7% as at December 31, 2014) and  is recorded at amortized cost using the effective interest rate method. Interest is paid semi-annually. The Company has pledged its interest in Emer as a general guarantee for its senior financing. The senior financing matures in 2017.
	(2)         A total of $7,521 Prins senior financing was assumed on the acquisition of Prins (note 4a). Principal of $3,891 was repaid on December 2, 2014. The senior financing agreement bears interest at the 3-month Euribor plus 3.5% (3.6% as at December 31, 2014). Interest is paid quarterly. The Company has pledged its interest in Prins as a general guarantee for its senior financing. The senior financing matures in 2016.
	(3)         The Prins senior mortgage loan was assumed on the acquisition of Prins (note 4a). The senior mortgage loan bears interest at 3-month Euribor plus 1% (1.1% as at December 31, 2014). Interest is paid quarterly. The Company has pledged its interest in Prins's building as a general guarantee for its senior mortgage loan. The senior mortgage loan matures in 2020.
Other Bank Financing [Member]
Schedule of Long-term Debt Instruments [Table Text Block]		December 31, 2014		December 31, 2013
	Emer other financing (1)	$	1,129	$	247
	Prins other financing (2)		1,424		—
	Other financing		93		156
		$	2,646	$	403
	(1)          Emer other financing consists of various unsecured bank financing arrangements that carry rates of interest ranging from 1.01% to  2.90% (2013 - 1.01% to 8.00%) and are payable on maturity dates ranging from June 23, 2015 to June 23, 2017.
	(2)         Prins other bank financing consists of a credit facility for maximum borrowings of €2,000. The credit facility bears interest at the 3 month Euribor + 3.5% (3.6% as of December 31, 2014). The credit facility is governed by an accounts receivable list requirement limiting such borrowings to 60% of accepted accounts receivable.

Warranty_liability_Tables

Warranty liability (Tables)	12 Months Ended
	Dec. 31, 2014
Product Warranties Disclosures [Abstract]
Schedule of Product Warranty Liability [Table Text Block]	A continuity of the warranty liability is as follows:
							Years ended December 31,
		2014		2013		2012
	Balance, beginning of period	$	28,845	$	6,380	$	4,401
	Warranty assumed on acquisition		1,952		582		—
	Warranty claims		-10,709		-5,397		-3,099
	Warranty accruals		2,734		4,153		5,303
	Change in estimate		—		22,837		—
	Impact of foreign exchange changes		287		290		-225
	Balance, end of period	$	23,109	$	28,845	$	6,380
	Less: Current portion		-9,696		-9,955		-2,072
	Long-term portion	$	13,413	$	18,890	$	4,308

Other_longterm_liabilities_Tab

Other long-term liabilities (Tables)	12 Months Ended
	Dec. 31, 2014
Other Liabilities Disclosure [Abstract]
Schedule of Other Long Term Liabilities [Table Text Block]		December 31,		December 31,
		2014		2013
	Severance indemnity (a)	$	1,519	$	1,547
	Contingent consideration payable related to AFV acquisition (b)		1,240		878
	Derivative Liability (note 13a)		86		—
	Deferred lease inducements		—		16
		$	2,845	$	2,441
	Current portion (included in accounts payable and accrued liabilities, other payables)		-1,240		—
		$	1,605	$	2,441
	(a)         Italian law requires companies to make a mandatory termination payment to employees. It is paid, as a lump sum, when the employment ends for any reason such as retirement, resignation or layoff. The severance indemnity liability is calculated in accordance with local civil and labour laws based on each employee’s length of service, employment category and remuneration. There is no vesting period or funding requirement associated with the liability. The liability recorded in the consolidated balance sheet is the amount that the employee would be entitled to if the employee terminates immediately. This liability for severance indemnities relates primarily to the Company’s employees in Italy.
	(b)         The total purchase price to acquire AFV also includes earn-out payments payable in the Company’s shares and tied to revenue and production milestones to be achieved no later than December 31, 2014. This contingent consideration has a fair value of $407 as at December 31, 2014 (December 31, 2013 - $427).

Share_capital_stock_options_an1

Share capital, stock options and other stock-based plans (Tables)	12 Months Ended
	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]	A summary of the status of the Company’s stock option plan as of December 31, 2014, December 31, 2013 and December 31, 2012 and changes during the periods then ended are presented as follows:
		December 31, 2014				December 31, 2013				December 31, 2012
				Weighted				Weighted				Weighted
				average				average				average
				exercise				exercise				exercise
		Number of		price		Number of		price		Number of		price
		shares		(CDN $)		shares		(CDN $)		shares		(CDN $)
	Outstanding, beginning of period		816,450	$	30.2		996,047	$	27.78		328,027	$	8.96
	Granted		—		—		—		—		770,727		33.77
	Exercised		-43,071		6.17		-111,986		6.8		-93,044		10.49
	Forfeited/expired		-741,156		33.82		-67,611		33.72		-9,663		33.36
	Outstanding, end of period		32,223	$	17.64		816,450	$	30.2		996,047	$	27.78
	Options exercisable, end of period		32,223	$	17.64		305,506	$	24.15		226,487	$	8.06
Schedule Of Share Based Compensation Arrangement By Share Based Payment Award Intrinsic Value [Table Text Block]	The aggregate intrinsic value of the Company’s stock option awards and share units at December 31, 2014 and 2013 are as follows:
		December 31,		December 31,
		2014		2013
		CDN$		CDN$
	Stock options:
	Outstanding	$	—	$	1,337
	Exercisable		—		1,337
	Exercised		364		2,667
	Share units:
	Outstanding	$	23,433	$	24,960
	Exercisable		624		4,670
	Exercised		7,238		18,041
Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]	Stock-based compensation associated with the Unit plans and the stock option plan is included in operating expenses as follows:
		Years ended December 31,
		2014		2013		2012
	Research and development	$	1,749	$	2,195	$	2,251
	General and administrative		5,884		10,201		6,752
	Sales and marketing		2,050		1,887		3,465
		$	9,683	$	14,283	$	12,468
Westport Omnibus Plan and the former Amended and Restated Unit Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]	A continuity of the Units issued under the Westport Omnibus Plan and the former Amended and Restated Unit Plan as of December 31, 2014, December 31, 2013 and December 31, 2012 are as follows:
		December 31, 2014				December 31, 2013				December 31, 2012
				Weighted				Weighted				Weighted
				average				average				average
				grant				grant				grant
				date fair				date fair				date fair
		Number of		value		Number of		value		Number of		value
		units		(CDN $)		units		(CDN $)		units		(CDN $)
	Outstanding, beginning of period		1,200,591	$	23.68		1,095,094	$	20.68		1,250,917	$	18.04
	Granted		5,792,162		10.54		742,140		30.21		185,705		35.99
	Exercised/Vested		-608,975		19.52		-448,526		24.44		-337,228		19.34
	Forfeited/expired		-1,045,905		21.75		-188,117		29.8		-4,300		19.67
	Outstanding, end of period		5,337,873	$	10.27		1,200,591	$	23.68		1,095,094	$	20.68
	Units outstanding and exercisable, end of period		142,166	$	11.67		224,638	$	11.2		262,615	$	8.86

Research_and_development_expen1

Research and development expenses (Tables)	12 Months Ended
	Dec. 31, 2014
Research and Development [Abstract]
Research and Development Expense [Table Text Block]	The research and development expenses had been incurred and program funding had been received or receivable are as follows:
		Years ended December 31,
		2014		2013		2012
	Research and development expenses	$	77,472	$	91,772	$	74,040
	Government assistance (note 16)		-892		-640		-842
	Research and development	$	76,580	$	91,132	$	73,198

Income_taxes_Tables

Income taxes (Tables)	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	(a)          The Company’s income tax provision differs from that calculated by applying the combined enacted Canadian federal and provincial statutory income tax rate of 26% for the year ended December 31, 2014 (year ended December 31, 2013 – 26%; nine months ended December 31, 2012 – 25%) as follows:
		Years ended December 31,
		2014		2013		2012
	Loss before income taxes	$	-150,197	$	-184,537	$	-97,036
	Expected income tax recovery		-39,051		-47,979		-24,259
	Increase (reduction) in income taxes resulting from:
	Non-deductible stock-based compensation		2,495		3,619		3,019
	Other permanent differences		-446		-2,562		-2,158
	Withholding taxes		969		590		1,187
	Change in enacted rates		—		—		62
	Foreign tax rate differences, foreign exchange and other adjustments		7,409		3,858		-382
	Non-taxable income from equity investment		-3,739		-2,851		-3,308
	Change in valuation allowance		25,784		37,391		27,577
	Goodwill impairment		4,748		8,807		—
	Change in uncertain tax position		1,252		—		—
	Income tax expense (recovery)	$	-579	$	873	$	1,738
Schedule of Deferred Tax Assets and Liabilities [Table Text Block]	(b)	The significant components of the deferred income tax assets and liabilities are as follows:
		December 31, 2014		December 31, 2013
	Deferred income tax assets:
	Net loss carry forwards	$	129,258	$	108,083
	Intangible assets		4,091		4,276
	Property, plant and equipment		6,836		5,446
	Financing and share issuance costs		1,533		2,696
	Warranty liability		5,131		5,726
	Deferred revenue		1,416		1,191
	Inventory		2,336		2,017
	Research and development		2,733		2,341
	Other		7,262		6,410
	Total gross deferred income tax assets		160,596		138,186
	Valuation allowance		-152,207		-126,424
	Total deferred income tax assets		8,389		11,762
	Deferred income tax liabilities:
	Intangible assets		6,386		9,884
	Property, plant and equipment		2,754		3,132
	Other		774		650
	Total deferred income tax liabilities		9,914		13,666
	Total net deferred income tax liabilities	$	1,525	$	1,904
	Allocated as follows:
	Current deferred income tax assets		3,556		3,109
	Current deferred income tax liabilities		-398		-468
	Long-term deferred income tax assets		271		379
	Long-term deferred income tax liabilities		-4,954		-4,903
	Total net deferred income tax liabilities	$	-1,525	$	-1,883
Summary of Valuation Allowance [Table Text Block]	The following is a summary of the changes in the deferred income tax asset valuation allowance:
		Year ended		Year ended
		December 31, 2014		December 31, 2013
	Beginning balance	$	126,424	$	89,033
	Additions		25,783		37,391
	Reductions		—		—
	Ending valuation allowance	$	152,207	$	126,424
Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]	(c)	The components of the Company’s income tax expense (recovery) are as follows:
		Income tax expense (recovery)
		Net income (loss)
		before income
		taxes		Current		Deferred		Total
	Year ended December 31, 2014:
	Canada	$	-87,783		165		301	$	466
	United States		-49,577		8		—		8
	Italy		-3,834		521		-1,463		-942
	Other		-9,003		-88		-23		-111
		$	-150,197	$	606	$	-1,185	$	-579
	Year ended December 31, 2013:
	Canada	$	-99,188	$	444	$	89	$	533
	United States		-31,019		56		-295		-239
	Italy		-27,247		836		-311		525
	Other		-27,083		78		-24		54
		$	-184,537	$	1,414	$	-541	$	873
	Year ended December 31, 2012:
	Canada	$	-93,688	$	1,339	$	53	$	1,392
	United States		-1,589		-62		—		-62
	Italy		-318		775		25		800
	Other		-1,441		95		-487		-392
		$	-97,036	$	2,147	$	-409	$	1,738
Summary of Operating Loss Carryforwards [Table Text Block]	The Company has loss carry-forwards in the various tax jurisdictions available to offset future taxable income as follows:
	Expiring in:	2015		2016		2017		2018		2019		2020 and later		Total
	Canada		$—		$—		$—		$—		$—	$	387,553,717	$	387,553,717
	Italy		—		—		—		—		—		6,429,576		6,429,576
	United States		—		—		—		—		—		55,353,513		55,353,513
	Sweden		—		—		—		—		—		13,710,864		13,710,864
	Other		—		—		—		1,085,596		6,725,731		7,834,119		15,645,446
	Total		$—		$—		$—	$	1,085,596	$	6,725,731	$	470,881,789	$	478,693,116
Summary of Income Tax Contingencies [Table Text Block]	A reconciliation of the change in the reserves for uncertain tax positions from January 1, 2014 to December 31, 2014 is as follows:
	Balance as of January 1, 2014	$	—
	Tax positions related to the current year:
	Additions		—
	Reductions		—
		$	—
	Tax positions related to prior years:
	Additions		1,230
	Reductions		—
	Settlements		—
	Lapses in statutes of limitations		—
	Balance as of December 31, 2014	$	1,230

Related_party_transactions_Tab

Related party transactions (Tables)	12 Months Ended
	Dec. 31, 2014
Related Party Transactions [Abstract]
Schedule of Related Party Transactions [Table Text Block]	Cost reimbursements from CWI consisted of the following:
		Years ended December 31,
		2014		2013		2012
	Research and development	$	3	$	178	$	160
	General and administrative		1,548		1,351		2,621
	Sales and marketing		4,935		4,725		3,683
		$	6,486	$	6,254	$	6,464

Commitments_and_contingencies_

Commitments and contingencies (Tables)	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]	The Company has obligations under operating lease arrangements that require the following minimum annual payments during the respective fiscal years:
	2015	$	3,946
	2016		4,978
	2017		5,890
	2018		4,969
	2019		4,960
	Thereafter		33,125
		$	57,868

Segmented_information_Tables

Segmented information (Tables)	12 Months Ended
	Dec. 31, 2014
Segment Reporting [Abstract]
Schedule of Segment Reporting Information [Table Text Block]		Years ended December 31,
		2014		2013		2012
	Revenue:
	Applied Technologies	$	86,168	$	93,216	$	91,675
	On-Road Systems		37,031		55,090		37,558
	Off-Road Systems		3,789		3,309		3,149
	Corporate and Technology Investments		3,581		12,417		23,244
	CWI		337,234		310,651		198,015
	WWI		618,465		466,580		272,086
	Total segment revenues		1,086,268		941,263		625,727
	Less: equity investees' revenue		-955,699		-777,231		-470,101
	Total consolidated revenues	$	130,569	$	164,032	$	155,626
	Net consolidated operating income (loss) excluding depreciation and amortization, losses on impairments, write-downs and disposals, provision for inventory purchase commitments, foreign exchange loss (gain), bank charges and other:
	Applied Technologies	$	-5,204	$	6,635	$	9,820
	On-Road Systems		-14,431		-59,843		-40,937
	Off-Road Systems		-2,744		-14,218		-13,653
	Corporate and Technology Investments		-87,363		-83,546		-50,211
	CWI		21,555		23,539		35,368
	WWI		78,502		14,496		9,765
	Total segment operating loss		-9,685		-112,937		-49,848
	Less: equity investees’ operating income		-100,057		-38,035		-45,133
	Net consolidated operating loss excluding depreciation and amortization, losses on impairments, write-downs and disposals, provision for inventory purchase commitments, foreign exchange (gain) loss, bank charges and other:		-109,742		-150,972		-94,981
	Depreciation and amortization:
	Applied Technologies		8,012		7,838		7,905
	On-Road Systems		5,561		3,186		1,028
	Off-Road Systems		—		450		83
	Corporate and Technology Investments		5,093		4,814		2,379
	Provision for inventory purchase commitments (On-Road Systems)		4,106		—		—
	Losses on impairments, write-downs and disposals
	Corporate and Technology Investments		3,458		31,564		—
	On-Road Systems		26,146		9,959		—
			52,376		57,811		11,395
	Net consolidated operating loss before foreign exchange (gain) loss, bank charges and other		-162,118		-208,783		-106,376
	Foreign exchange (gain) loss, bank charges and other		-2,731		-14,573		1,922
	Loss from operations		-159,387		-194,210		-108,298
	Interest on long-term debt and other income (expenses), net		-5,032		-3,771		-4,928
	Income from investment accounted for by the equity method		14,222		13,444		16,190
	Loss before income taxes	$	-150,197	$	-184,537	$	-97,036
Schedule of Assets by Segment [Table Text Block]		Years ended December 31,
		2014		2013		2012
	Total additions to long-lived assets excluding business combinations:
	Applied Technologies	$	938	$	4,408	$	3,000
	On-Road Systems		1,340		15,555		10,306
	Off-Road Systems		—		908		1,481
	Corporate and Technology Investments		7,971		5,579		16,565
		$	10,249	$	26,450	$	31,352
Schedule Of Geographical Revenue Information [Table Text Block]	It is impracticable for the Company to provide geographical revenue information by individual countries; however, it is practicable to provide it by geographical regions.  Product and service and other revenues are attributable to geographical regions based on location of the Company’s customers and presented as a percentage of the Company’s product and service revenues are as follows:
		% of total product revenue and service and other revenue
		Years ended December 31,
		2014		2013		2012
	Americas (including United States)		40		42		38
	Asia (including China)		12		11		9
	Other (including Italy)		48		47		53
Schedule Of Allocation Of The Total Assets [Table Text Block]	Total assets are allocated as follows:
		December 31, 2014		December 31, 2013
	Applied Technologies	$	151,428	$	144,803
	On-Road Systems		130,461		111,323
	Off-Road Systems		1,042		6,564
	Corporate and Technology Investments and unallocated assets		54,764		228,981
	CWI		172,941		115,343
	WWI		182,215		131,146
			692,851		738,160
	Less: equity investees’ total assets		355,156		246,489
	Total consolidated assets	$	337,695	$	491,671
Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas [Table Text Block]	Long-lived assets information by geographic area:
		December 31, 2014		December 31, 2013
	Italy	$	53,319	$	66,918
	Netherlands		9,944		—
	Canada		25,083		30,713
	United States		20,320		47,322
	Sweden		208		322
	China		6,329		8,675
	Australia		1,233		1,360
			116,436		155,310
	Less: equity investees’ long-lived assets		7,030		8,117
	Total consolidated long-lived assets	$	109,406	$	147,193

Financial_instruments_Tables

Financial instruments (Tables)	12 Months Ended
	Dec. 31, 2014
Financial Instruments Disclosure [Abstract]
Contractual Obligation, Fiscal Year Maturity Schedule [Table Text Block]	The following are the contractual maturities of financial obligations as at December 31, 2014:
		Carrying		Contractual
		amount		cash flows		< 1 year		1-3 years		4-5 years		>5 years
	Accounts payable and accrued liabilities	$	55,502	$	55,502	$	55,502		$—		$—		$—
	Unsecured subordinated debentures (1)		46,491		68,613		4,950		63,663		—		—
	Senior financing (2)		15,910		16,565		6,314		8,353		779		1,120
	Senior revolving financing (3)		12,101		12,743		315		12,429		—		—
	Other bank financing (4)		2,646		3,135		1,050		478		121		1,485
	Capital lease obligations		1,394		1,490		626		665		200		—
	Operating lease commitments		—		57,867		3,946		10,868		9,929		33,125
	Royalty payments (5)		1,294		15,927		1,164		2,327		2,327		10,108
		$	135,338	$	231,842	$	73,867	$	98,783	$	13,356	$	45,838
	(1) Includes interest at 9%.
	(2) Includes interest at rates disclosed in note 13(b) in effect at December 31, 2014.
	(3) Includes interest at rates disclosed in note 13(c) in effect at December 31, 2014.
	(4) Includes interest at rates disclosed in note 13(d) in effect at December 31, 2014.
	(5) From fiscal 2011 to 2015 inclusive, the Company is obligated to pay annual royalties equal to the greater of $1,164 (CDN$1,350) or 0.33% of the Company's gross annual revenue from all sources, provided that gross revenue exceeds $12,693 (CDN$13,500) in any aforementioned fiscal year, up to a maximum of $26,514 (CDN$28,189).  The Company has assumed the minimum required payments.
Schedule of Foreign Exchange Contracts, Statement of Financial Position [Table Text Block]	The Company’s functional currency is the Canadian dollar. The U.S. dollar and the Euro carrying amount of financial instruments subject to exposure to foreign currency risk in the consolidated balance sheet  at December 31, 2014 is as follows:
		U.S. dollars
	Cash and cash equivalents	$	69,899
	Short-term investments		500
	Accounts receivable		14,304
	Accounts payable		4,012
			Euros
	Cash and cash equivalents	€	9,190
	Accounts receivable		38,916
	Accounts payable		27,667

Company_organization_and_opera1

Company organization and operations (Details Textual)	12 Months Ended
	Dec. 31, 2014
	l
Minimum [Member]
Capacity of Medium Petroleum Based Fuel Engine	5.9
Capacity of Heavy Duty Petroleum Based Fuel Engine	11
Capacity of High Horsepower Petroleum Based Fuel Engine	16
Maximum [Member]
Capacity of Light Petroleum Based Fuel Engine	5.9
Capacity of Medium Petroleum Based Fuel Engine	10
Capacity of Heavy Duty Petroleum Based Fuel Engine	16

Significant_accounting_policie3

Significant accounting policies (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Canadian dollar
Foreign Currency Exchange Rate, Translation	0.86	0.94
Average Foreign Currency Exchange Rate Translation	0.91	0.97
Australian dollar
Foreign Currency Exchange Rate, Translation	0.82	0.89
Average Foreign Currency Exchange Rate Translation	0.9	0.97
Euro
Foreign Currency Exchange Rate, Translation	1.21	1.38
Average Foreign Currency Exchange Rate Translation	1.33	1.33
RMB
Foreign Currency Exchange Rate, Translation	0.16	0.17
Average Foreign Currency Exchange Rate Translation	0.16	0.16
Swedish Krona
Foreign Currency Exchange Rate, Translation	0.13	0.16
Average Foreign Currency Exchange Rate Translation	0.15	0.15

Significant_accounting_policie4

Significant accounting policies (Details 1)	12 Months Ended
	Dec. 31, 2014
Buildings [Member]
Property, Plant and Equipment, Useful Life (in years)	15 years
Property, Plant and Equipment, Depreciation Methods	Straight-line
Computer equipment and software [Member]
Property, Plant and Equipment, Useful Life (in years)	3 years
Property, Plant and Equipment, Depreciation Methods	Straight-line
Furniture and fixtures [Member]
Property, Plant and Equipment, Useful Life (in years)	5 years
Property, Plant and Equipment, Depreciation Methods	Straight-line
Machinery and equipment [Member]
Property, Plant and Equipment, Depreciation Methods	Straight-line
Machinery and equipment [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life (in years)	8 years
Machinery and equipment [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life (in years)	10 years
Leasehold improvements [Member]
Property, Plant and Equipment, Estimated Useful Lives	Lease term
Property, Plant and Equipment, Depreciation Methods	Straight-line

Significant_accounting_policie5

Significant accounting policies (Details Textual) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Retained Earnings (Accumulated Deficit), Total	($764,960)	($615,342)
Cash and Cash Equivalents, at Carrying Value, Total	$93,282	$178,513	$188,958	$63,285
Revenue Recognition, Multiple-deliverable Arrangements, Determination of Selling Price, Method	the Company requires that a substantial majority of the selling prices for a product or service falls within a reasonably narrow pricing range, generally evidenced by the pricing rates of approximately 85% of such historical stand-alone transactions falling within plus or minus 10% of the median rate.
Minimum [Member]
Finite-Lived Intangible Asset, Useful Life	5 years
Maximum [Member]
Finite-Lived Intangible Asset, Useful Life	20 years

Business_Combinations_Details

Business Combinations (Details)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2014	Dec. 31, 2014
	BAF Technologies Inc [Member]	Prins Autogassystemen Holding B.V. [Member]	Prins Autogassystemen Holding B.V. [Member]
	USD ($)	USD ($)	EUR (€)
Other tangible assets, including cash	$9,116	$13,138
Property, plant and equipment	905	3,824
Intangible assets subject to amortization	7,729	3,024
Goodwill	18,542	3,221
Total assets acquired	36,292	23,207
Current liabilities		7,211
Deferred income tax liabilities		979
Debt assumed (note 13b and c)		11,905	-9,700
Less: total liabilities	-6,594	20,095
Total net assets acquired	29,698	3,112
Paid to sellers		3,112
Payable to Clean Energy	2,322
Common shares issued	24,091
Common shares to be issued	3,285
Business Combination, Consideration Transferred	$29,698

Business_Combinations_Details_

Business Combinations (Details 1) (USD $)	12 Months Ended			1 Months Ended	6 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014	Dec. 31, 2013
Revenue for the period	$130,569	$164,032	$155,626
Pro forma revenue for the period	161,562	202,166
Net loss for the period	-149,618	-185,410	-98,774
Pro forma net loss for the period	-149,527	-180,284
Prins Autogassystemen Holding B.V. [Member]
Revenue for the period	30,993	30,885		1,196
Net loss for the period	91	9,164		-301
BAF Technologies Inc [Member]
Revenue for the period	0	7,249			17,097
Pro forma revenue for the period		171,281	181,972
Net loss for the period	0	-4,038			3,512
Pro forma net loss for the period		($189,448)	($100,946)

Business_Combinations_Details_1

Business Combinations (Details 2) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	5 years
BAF Technologies Inc [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill, Total	7,729
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	7 years
BAF Technologies Inc [Member] | Customer Relationships [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill, Total	6,350
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	8 years
BAF Technologies Inc [Member] | Core Technologies [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill, Total	160
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	10 years
Other Intangible Assets [Member] | BAF Technologies Inc [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill, Total	1,219
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	3 years

Business_Combinations_Details_2

Business Combinations (Details 3) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenue	$161,562	$202,166
Net loss	-149,527	-180,284
BAF Technologies Inc [Member]
Revenue		171,281	181,972
Net loss		($189,448)	($100,946)

Business_Combinations_Details_3

Business Combinations (Details Textual)

12 Months Ended

12 Months Ended

1 Months Ended

6 Months Ended

12 Months Ended

1 Months Ended

3 Months Ended

1 Months Ended

12 Months Ended

1 Months Ended

In Thousands, except Share data, unless otherwise specified

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2012

Jun. 28, 2013

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Jun. 28, 2013

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Jun. 28, 2013

Mar. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2014

Jun. 28, 2013

USD ($)

USD ($)

USD ($)

USD ($)

Land and Building [Member]

Minimum [Member]

Maximum [Member]

BAF Technologies Inc [Member]

BAF Technologies Inc [Member]

BAF Technologies Inc [Member]

BAF Technologies Inc [Member]

BAF Technologies Inc [Member]

BAF Technologies Inc [Member]

BAF Technologies Inc [Member]

BAF Technologies Inc [Member]

BAF Technologies Inc [Member]

Clean Energy [Member]

Clean Energy [Member]

Prins Autogassystemen Holding B.V. [Member]

Prins Autogassystemen Holding B.V. [Member]

Prins Autogassystemen Holding B.V. [Member]

Prins Autogassystemen Holding B.V. [Member]

Prins Autogassystemen Holding B.V. [Member]

Prins Autogassystemen Holding B.V. [Member]

Stock Purchase Agreement [Member]

USD ($)

USD ($)

USD ($)

USD ($)

Customer Relationships [Member]

Deferred Income Tax Charge [Member]

Inventory Valuation and Obsolescence [Member]

Minimum [Member]

Maximum [Member]

USD ($)

USD ($)

USD ($)

USD ($)

EUR (€)

USD ($)

Land and Building [Member]

Inventory Valuation and Obsolescence [Member]

BAF Technologies Inc [Member]

USD ($)

USD ($)

USD ($)

USD ($)

Business Acquisition, Percentage of Voting Interests Acquired

100.00%

100.00%

100.00%

100.00%

Business Acquisition, Equity Interest Issued or Issuable, Number of Shares

718,485

97,975

816,460

Business Acquisition, Share Price

$30.62

$33.53

Business Acquisition, Equity Interest Issued or Issuable, Value Assigned

$24,091

$3,285

Payments to Acquire Interest in Subsidiaries and Affiliates, Total

5,000

Fair Value Of Products And Services

2,678

Business Combination Consideration Payable

5,000

Business Combination Consideration Payable In Excess

2,322

Business Combination, Acquisition Related Costs

493

342

Business Acquisitions Purchase Price Allocation Current Assets Cash And Cash Equivalents

1,178

61

61

Finite-Lived Intangible Asset, Useful Life

15 years

5 years

20 years

8 years

3 years

10 years

5 years

5 years

Payments to Acquire Businesses, Gross

15,017

12,200

Revenue, Net, Total

130,569

164,032

155,626

17,097

0

7,249

1,196

30,993

30,885

Net Income (Loss), Including Portion Attributable to Noncontrolling Interest, Total

-149,618

-185,410

-98,774

3,512

0

-4,038

-301

91

9,164

Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net

3,112

3,112

2,500

Business Combination, Consideration Transferred, Other

296

5,792

3,824

4,975

Business Acquisition, Date of Acquisition Agreement

28-Jun-13

2-Dec-14

2-Dec-14

Goodwill, Acquired During Period

18,542

3,221

Finite-lived Intangible Assets Acquired

3,024

Acquired Finite-lived Intangible Assets, Weighted Average Useful Life

5 years

7 years

8 years

Business Combinations, Purchase Price Allocation, Notes Payable and Long-term Debt

($11,905)

($11,905)

€ 9,700

Accounts_Receivable_Details

Accounts Receivable (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Customer trade receivable	$43,256	$54,017
Government funding receivable	38	483
Due from joint venture (note 20)	2,538	3,621
Other receivables	3,269	2,689
Income tax receivable	499	77
Allowance for doubtful accounts	-2,751	-1,572
Accounts Receivable Net Current	$46,849	$59,315

Inventories_Details

Inventories (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Purchased parts	$28,227	$23,228
Work-in-process	4,879	10,770
Finished goods	8,718	6,628
Inventory Net	$41,824	$40,626

Inventories_Details_Textual

Inventories (Details Textual) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Inventory Write-down	$2,102	$4,925	$0

Longterm_investments_Details

Long-term investments (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Long Term Investments	$33,324		$22,128
Weichai Westport Inc [Member]
Long Term Investments	18,791	[1]	14,534	[1]
Cummins Westport, Inc. [Member]
Long Term Investments	13,196		7,191
Other Equity Accounted for Investees [Member]
Long Term Investments	$1,337		$403
[1]	On July 3, 2010, the Company invested $4,316 under an agreement with Weichai Holding Group Co. Ltd. and Hong Kong Peterson (bCNGb) Equipment Ltd. to form Weichai Westport Inc. (bWWIb). On October 11, 2011, the Company invested an additional $955 in WWI. The Company has a 35% equity interest in WWI. For the year ended December 31, 2014, the Company recognized its share of WWIbs income of $6,027 (year ended December 31, 2013 - $4,264; year ended December 31, 2012 - $2,881), as income from investment accounted for by the equity method. Assets, liabilities, revenue and expenses of WWI as of and for the periods presented are as follows: December 31, 2014 December 31, 2013 Current assets: Cash and short-term investments $ 11,734 $ 4,696 Accounts receivable 72,121 31,967 Inventory 83,594 80,412 Other current assets 1,249 176 Long-term assets Property, plant and equipment 5,736 7,021 Deferred income tax assets 7,781 6,874 Total assets $ 182,215 $ 131,146 Current liabilities: Accounts payable and accrued liabilities $ 128,838 $ 93,016 Total liabilities $ 128,838 $ 93,016 Years ended December 31, 2014 2013 2012 Product revenue $ 618,465 $ 466,580 $ 272,086 Cost of revenue and expenses: Cost of product revenue 539,963 429,238 247,299 Operating expenses 58,208 22,846 15,022 598,171 452,084 262,321 Income before income taxes 20,294 14,496 9,765 Income tax expense 3,076 2,315 1,536 Income for the period $ 17,218 $ 12,181 $ 8,229

Longterm_investments_Details_1

Long-term investments (Details 1) (Weichai Westport Inc [Member], USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Weichai Westport Inc [Member]
Current assets:
Cash and short-term investments	$11,734	$4,696
Accounts receivable	72,121	31,967
Inventory	83,594	80,412
Other current assets	1,249	176
Long-term assets
Property, plant and equipment	5,736	7,021
Deferred income tax assets	7,781	6,874
Total assets	182,215	131,146
Current liabilities:
Accounts payable and accrued liabilities	128,838	93,016
Total liabilities	128,838	93,016
Product revenue	618,465	466,580	272,086
Cost of revenue and expenses:
Cost of product revenue	565,943	429,238	247,299
Operating expenses	32,227	22,846	15,022
Equity Method Investment Summarized Financial Information Cost of Revenue and Expenses	598,170	452,084	262,321
Income before income taxes	20,295	14,496	9,765
Income tax expense	3,076	2,315	1,536
Income for the period	$17,219	$12,181	$8,229

Longterm_investments_Details_2

Long-term investments (Details 2) (Cummins Westport, Inc. [Member], USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cummins Westport, Inc. [Member]
Current assets:
Cash and short-term investments	$107,415	$73,736
Accounts receivable	12,741	4,645
Current portion of deferred income tax assets	21,967	13,958
Other current assets	116	210
Long-term assets:
Property, plant and equipment	1,294	1,096
Deferred income tax assets	29,408	21,698
Total assets	172,941	115,343
Current liabilities:
Current portion of warranty liability	48,818	18,395
Current portion of deferred revenue	8,029	5,478
Accounts payable and accrued liabilities	6,419	7,772
Current liabilities	63,266	31,645
Long-term liabilities:
Warranty liability	43,983	49,174
Deferred revenue	34,345	17,815
Other long-term liabilities	2,771	2,400
Long-term liabilities	81,099	69,389
Total liabilities	144,365	101,034
Product revenue	283,551	261,012	161,741
Parts revenue	53,683	49,639	36,274
Equity Method Investment Summarized Financial Information Total revenue	337,234	310,651	198,015
Cost of revenue and expenses:
Cost of product and parts revenue	270,832	246,403	136,575
Research and development	21,131	21,522	12,114
General and administrative	1,202	1,348	1,417
Sales and marketing	22,514	17,839	12,541
Foreign exchange (gain) loss	34	-7	-18
Bank charges, interest and other	805	607	472
Equity Method Investment Summarized Financial Information Cost of Revenue and Expenses	316,518	287,712	163,101
Income from operations	20,716	22,939	34,914
Interest and investment income	260	117	530
Income before income taxes	20,976	23,056	35,444
Income tax expense (recovery):
Current	21,514	24,600	16,362
Deferred	-15,719	-18,566	-6,517
Equity Method Investment Summarized Financial Information Income tax expense (recovery)	5,795	6,034	9,845
Income for the period	$15,181	$17,022	$25,599

Longterm_investments_Details_T

Long-term investments (Details Textual) (USD $)	0 Months Ended	12 Months Ended			1 Months Ended
In Thousands, unless otherwise specified	Oct. 11, 2011	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jul. 31, 2010
Equity Method Investment, Profit Sharing Percentage		75.00%
Payments to Acquire Equity Method Investments	$955
Income (Loss) from Equity Method Investments		14,222	13,444	16,190
Equity Method Investment, Ownership Percentage		50.00%
Cummins Westport, Inc. [Member]
Equity Method Investment, Profit Sharing Percentage		25.00%
Equity Method Investment, Summarized Financial Information, Net Income (Loss)		15,181	17,022	25,599
Income (Loss) from Equity Method Investments		8,136	9,433	13,232
Equity Method Investment, Ownership Percentage		50.00%
Westport Light Duty Canada Inc [Member]
Equity Method Investment, Profit Sharing Percentage					35.00%
Equity Method Investment, Summarized Financial Information, Net Income (Loss)					4,316
Income (Loss) from Equity Method Investments		$6,027	$4,264	$2,881

Variable_Interest_Entities_Det

Variable Interest Entities (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Accounts Receivable [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Carrying Amount	$2,538	$3,621
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	2,538	3,621
Equity Method Investments [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Carrying Amount	13,196	7,191
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	$13,196	$7,191

Variable_Interest_Entities_Det1

Variable Interest Entities (Details Textual)	1 Months Ended
	Feb. 20, 2012	Dec. 31, 2014
Variable Interest Entity [Line Items]
Equity Method Investment, Ownership Percentage		50.00%
Westport Innovations Inc [Member]
Variable Interest Entity [Line Items]
Equity Method Investment, Ownership Percentage		50.00%
Description Of Profit Sharing Percentage	75.00%
Cummins Westport Inc [Member]
Variable Interest Entity [Line Items]
Equity Method Investment, Ownership Percentage		50.00%
Description Of Profit Sharing Percentage	25.00%

Property_plant_and_equipment_D

Property, plant and equipment (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Cost	$112,879	$117,411
Accumulated depreciation	54,745	50,062
Net book value	58,134	67,349
Land and buildings [Member]
Cost	3,015
Accumulated depreciation	0
Net book value	3,015
Computer equipment and software [Member]
Cost	9,277	9,652
Accumulated depreciation	7,063	6,174
Net book value	2,214	3,478
Furniture and fixtures [Member]
Cost	6,194	6,608
Accumulated depreciation	1,798	1,692
Net book value	4,396	4,916
Machinery and equipment [Member]
Cost	81,933	86,067
Accumulated depreciation	36,135	32,099
Net book value	45,798	53,968
Leasehold improvements [Member]
Cost	12,460	15,084
Accumulated depreciation	9,749	10,097
Net book value	$2,711	$4,987

Property_plant_and_equipment_D1

Property, plant and equipment (Details Textual) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Depreciation, Total	$14,106	$12,246	$8,131
Machinery and Equipment [Member]
Capital Leased Assets, Gross	16,572	18,788
Capital Leases, Balance Sheet, Assets by Major Class, Net, Total	$1,714	$5,465

Intangible_assets_Details

Intangible assets (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Cost	$38,698		$48,151
Accumulated amortization	10,778		9,807
Net book value	27,920		38,344
Patents and trademarks [Member]
Cost	18,425		20,974
Accumulated amortization	3,445		2,900
Net book value	14,980		18,074
Technology [Member]
Cost	6,449	[1]	7,468
Accumulated amortization	3,142	[1]	2,796
Net book value	3,307	[1]	4,672
Customer contracts [Member]
Cost	13,762	[1]	18,447	[2]
Accumulated amortization	4,163	[1]	3,886	[2]
Net book value	9,599	[1]	14,561	[2]
Other intangibles [Member]
Cost	62	[1]	1,262
Accumulated amortization	28	[1]	225
Net book value	$34	[1]	$1,037
[1]	The Company reviews its long-lived assets for impairment including property, plant and equipment, and intangible assets whenever events and changes in circumstances indicate that the carrying amount of the assets may not be recoverable. Based on the revenue and operating results and decline in the oil price, the Company concluded there were impairment indicators requiring the performance of a long-lived assets impairment test for customer contracts, technology and other intangibles as of November 30, 2014. Accordingly non-cash impairment charges aggregating to $5,823 were recorded during the year December 31, 2014 and reduces the carrying values of technology by $100, customer contracts by $5,323 and other intangibles by $400 for the On-Road Systems segment.
[2]	During the year ended December 31, 2013, there was a significant decline in revenue from the lower than expected adoption rate of natural gas vehicles in our customer contracts. An impairment analysis of the intangibles balance indicated that the carrying value exceeded the fair value of customer contracts. Accordingly, an intangible impairment charge of $1,721 related to customer contracts in Sweden was recognized in the On-Road Systems segment. The fair value of customer contracts was determined using the present value of expected cash flows discounted at a rate equivalent to a market participantbs weighted-average cost of capital.

Intangible_assets_Details_Text

Intangible assets (Details Textual) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Amortization of Intangible Assets	$4,560	$4,042	$3,264
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	3,345
Finite-Lived Intangible Assets, Amortization Expense, Year Two	3,345
Finite-Lived Intangible Assets, Amortization Expense, Year Three	3,345
Finite-Lived Intangible Assets, Amortization Expense, Year Four	3,345
Finite-Lived Intangible Assets, Amortization Expense, Year Five	3,345
Impairment of Intangible Assets, Finite-lived	5,823	1,721	0
Other Intangible Assets [Member]
Finite-Lived Intangible Assets, Period Increase (Decrease)	1,003
Customer Contracts [Member]
Finite-Lived Intangible Assets, Period Increase (Decrease)	4,705
Technology Equipment [Member]
Finite-Lived Intangible Assets, Period Increase (Decrease)	$115

Goodwill_Details

Goodwill (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Balance, beginning of period:	$41,500	$56,879
Impairment losses	-18,543	-34,964	0
Impact of foreign exchange changes	-2,826	1,043
Balance, end of period	23,352	41,500	56,879
Prins Autogassystemen Holding B.V. [Member]
Acquisition	3,221	0
BAF Technologies Inc [Member]
Acquisition	$0	$18,542

Goodwill_Details_Textual

Goodwill (Details Textual) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Goodwill, Impairment Loss	$18,543	$34,964	$0
Goodwill	23,352	41,500	56,879
Applied Technologies Segment [Member]
Goodwill, Impairment Loss		30,067
Goodwill	23,352
On Road Segment [Member]
Goodwill, Impairment Loss		$4,897

Accounts_payable_and_accrued_l2

Accounts payable and accrued liabilities (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Trade accounts payable	$41,796	$42,872
Accrued payroll	5,270	7,937
Accrued interest	1,237	893
Income taxes payable	580	709
Other payables (note 22b)	6,619	2,381
Accounts Payable, Current	$55,502	$54,792

Longterm_debt_Details

Long-term debt (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Debt and Capital Lease Obligations, Total	$78,542		$66,013
Current portion	-18,955		-53,025
Long-term Debt and Capital Lease Obligations, Total	59,587		12,988
Senior revolving financing [Member]
Debt and Capital Lease Obligations, Total	12,101	[1]	13,779	[1]
Other bank financing [Member]
Debt and Capital Lease Obligations, Total	2,646	[2]	403	[2]
Subordinated debenture notes [Member]
Debt and Capital Lease Obligations, Total	46,491	[3]	33,847	[3]
Senior financing [Member]
Debt and Capital Lease Obligations, Total	15,910	[4]	15,941	[4]
Capital lease obligations [Member]
Debt and Capital Lease Obligations, Total	$1,394	[5]	$2,043	[5]
[1]	The senior revolving financing facility bears interest at the 6-month Euribor plus 2.5% (2.6% as at December 31, 2014) and will be repaid through two principal payments of $6,050 (€5,000) on March 31, 2016 and October 2, 2017. Interest is paid semi-annually. The Company has pledged its interest in Emer as a general guarantee for its senior revolving financing.Throughout the entire term of these financing arrangements, the Company is required to meet certain financial and non-financial covenants. As of December 31, 2014, the Company is in compliance with all covenants under the financing arrangements.
[2]	December 31, 2014 December 31, 2013 Emer other financing (1) 1,129 247 Prins other financing (2) 1,424 B Other financing 93 156 2,646 403 (1) Emer other financing consists of various unsecured bank financing arrangements that carry rates of interest ranging from 1.01% to 2.90% (2013 - 1.01% to 8.00%) and are payable on maturity dates ranging from June 23, 2015 to June 23, 2017. (2) Prins other bank financing consists of a credit facility for maximum borrowings of €2,000. The credit facility bears interest at the 3 month Euribor + 3.5% (3.6% as of December 31, 2014). The credit facility is governed by an accounts receivable list requirement limiting such borrowings to 60% of accepted accounts receivable.
[3]	On September 23, 2011, the Company raised $33,720 (CDN$36,000) through the issuance of debentures to Macquarie Private Wealth Inc. (bMacquarieb) on a private placement basis (the bInitial Debenturesb). The Initial Debentures were unsecured and subordinated to senior indebtedness, matured on September 22, 2014, and bore interest at 9% per annum, payable in cash semi-annually in arrears on March 15 and September 15 of each year during the term, which commenced on March 15, 2012. The Initial Debentures were redeemable at the option of the Company at a price equal to $1,150 per $1,000 principal amount of the debentures on or before March 22, 2013. After March 22, 2013 and before maturity, the debentures were redeemedable at a price equal to $1,100 per $1,000 principal amount. On June 27, 2014, the Company raised $17,797 (CDN$19,000) through the issuance of debentures to Richardson GMP Limited (bRGMPb), formerly Macquarie Private Wealth Inc. on a private placement basis (the bAdditional Debenturesb). In conjunction with the issuance of the Additional Debentures, the Company amended the terms of the Initial Debentures (the bAmended Initial Debenturesb). The Amended Initial Debentures are ranked pari passu with the Additional Debentures and both shall be treated as the same series of debentures (the bNew Debenturesb) with the same terms. The New Debentures totaling $51,517 (CDN$55,000) are composed of the Additional Debentures $17,797 (CDN$19,000) and the Amended Initial Debentures $33,720 (CDN$36,000). The New Debentures are unsecured and subordinated to senior indebtedness, mature on September 15, 2017, and bear interest at 9% per annum, payable in cash semi-annually in arrears on March 15 and September 15 of each year during the term. The New Debentures are redeemable at the option of the Company at a price equal to $1,150 per $1,000 principal amount of the debentures after September 15, 2015 and on or before March 15, 2016. After March 15, 2016 and before maturity, the debentures can be redeemed at a price equal to $1,100 per $1,000 principal amount. The New Debentures contain an extension option that will allow each debenture holder to have the option to extend, a maximum of six times, the maturity date for an additional period of six months provided that greater than CDN$10,000 of the aggregate principal amount of the New Debentures remain outstanding. The Company has performed the assessment of embedded derivatives within the New Debentures and concluded that there is an embedded derivative that requires bifurcation related to the extension option from the New Debentures. The extension option was deemed not clearly and closely related to the New Debentures and is separately accounted for as a standalone derivative. The Company recorded this embedded derivative as a non-current liability on its consolidated balance sheet. At issuance on June 27, 2014, the embedded derivativebs fair value was determined to be $1,169 (CDN$1,249), which was recorded as a reduction to the carrying value of the New Debentures. The Company is accreting the carrying value of the debt to interest expense by using the effective interest method through to the maturity date of the New Debentures. The Company accreted $82 of the embedded derivative discount for the year ended December 31, 2014 (2013 $Nil ). The embedded derivative is subsequently adjusted to fair value at each reporting date, with the associated fair value loss (gain) recorded in interest and other income (loss). The fair value adjustment recorded for the year ended December 31, 2014 was $(1,082) (2013 $Nil). The derivative liability is included in other long term liabilities on the consolidated balance sheets. The Company determined the fair value of the embedded derivative using the Interest Rate Option Pricing Method which incorporated the Black-Karasinski model.
[4]	December 31, 2014 December 31, 2013 Emer Senior Financing (1) $ 9,376 $ 15,941 Prins Senior Financing (2) 3,630 B Prins Senior Mortgage Loan (3) 2,904 B $ 15,910 $ 15,941 (1) The senior financing agreement bears interest at the 6-month Euribor plus 2.5% (2.7% as at December 31, 2014) and is recorded at amortized cost using the effective interest rate method. Interest is paid semi-annually. The Company has pledged its interest in Emer as a general guarantee for its senior financing. The senior financing matures in 2017. (2) A total of $7,521 Prins senior financing was assumed on the acquisition of Prins (note 4a). Principal of $3,891 was repaid on December 2, 2014. The senior financing agreement bears interest at the 3-month Euribor plus 3.5% (3.6% as at December 31, 2014). Interest is paid quarterly. The Company has pledged its interest in Prins as a general guarantee for its senior financing. The senior financing matures in 2016. (3) The Prins senior mortgage loan was assumed on the acquisition of Prins (note 4a). The senior mortgage loan bears interest at 3-month Euribor plus 1% (1.1% as at December 31, 2014). Interest is paid quarterly. The Company has pledged its interest in Prins's building as a general guarantee for its senior mortgage loan. The senior mortgage loan matures in 2020. The principal repayment schedule of the senior financings are as follows for the years ended December 31: Emer Senior Financing Prins Senior Financing Prins Senior Mortgage Loan Total 2015 $ 4,020 $ 1,633 $ 363 $ 6,016 2016 4,239 1,997 363 6,599 2017 1,117 B 363 1,480 2018 B B 363 363 2019 and thereafter B B 1,452 1,452 $ 9,376 $ 3,630 $ 2,904 $ 15,910
[5]	The Company has capital lease obligations that have initial terms of three to five years at interest rates ranging from 3.07% to 4.93% (2013 - 3.07% to 7.32%). The capital lease obligations require the following minimum annual principal payments during the respective fiscal years: 2015 $ 522 2016 328 2017 327 2018 191 2019 26 $ 1,394

Longterm_debt_Details_1

Long-term debt (Details 1) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Long-term Debt	$15,910		$15,941
Emer Senior Financing [Member]
Long-term Debt	9,376	[1]	15,941	[1]
Prins Senior Financing [Member]
Long-term Debt	3,630	[2]	0	[2]
Prins Senior Mortgage Loan [Member]
Long-term Debt	$2,904	[3]	$0	[3]
[1]	The Emer S.p.A ("Emer") senior financing agreement bears interest at the 6-month Euribor plus 2.5% (2.7% as at December 31, 2014) and is recorded at amortized cost using the effective interest rate method. Interest is paid semi-annually. The Company has pledged its interest in Emer as a general guarantee for its senior financing. The senior financing matures in 2017.
[2]	A total of $7,521 Prins senior financing was assumed on the acquisition of Prins (note 4a). Principal of $3,891 was repaid on December 2, 2014. The senior financing agreement bears interest at the 3-month Euribor plus 3.5% (3.6% as at December 31, 2014). Interest is paid quarterly. The Company has pledged its interest in Prins as a general guarantee for its senior financing. The senior financing matures in 2016.
[3]	The Prins senior mortgage loan was assumed on the acquisition of Prins (note 4a). The senior mortgage loan bears interest at 3-month Euribor plus 1% (1.1% as at December 31, 2014). Interest is paid quarterly. The Company has pledged its interest in Prins's building as a general guarantee for its senior mortgage loan. The senior mortgage loan matures in 2020.

Longterm_debt_Details_2

Long-term debt (Details 2) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
2015	$6,016
2016	6,599
2017	1,480
2018	363
2019 and thereafter	1,452
Long-term Debt	15,910		15,941
Emer Senior Financing [Member]
2015	4,020
2016	4,239
2017	1,117
2018	0
2019 and thereafter	0
Long-term Debt	9,376	[1]	15,941	[1]
Prins Senior Financing [Member]
2015	1,633
2016	1,997
2017	0
2018	0
2019 and thereafter	0
Long-term Debt	3,630	[2]	0	[2]
Prins Senior Mortgage Loan [Member]
2015	363
2016	363
2017	363
2018	363
2019 and thereafter	1,452
Long-term Debt	$2,904	[3]	$0	[3]
[1]	The Emer S.p.A ("Emer") senior financing agreement bears interest at the 6-month Euribor plus 2.5% (2.7% as at December 31, 2014) and is recorded at amortized cost using the effective interest rate method. Interest is paid semi-annually. The Company has pledged its interest in Emer as a general guarantee for its senior financing. The senior financing matures in 2017.
[2]	A total of $7,521 Prins senior financing was assumed on the acquisition of Prins (note 4a). Principal of $3,891 was repaid on December 2, 2014. The senior financing agreement bears interest at the 3-month Euribor plus 3.5% (3.6% as at December 31, 2014). Interest is paid quarterly. The Company has pledged its interest in Prins as a general guarantee for its senior financing. The senior financing matures in 2016.
[3]	The Prins senior mortgage loan was assumed on the acquisition of Prins (note 4a). The senior mortgage loan bears interest at 3-month Euribor plus 1% (1.1% as at December 31, 2014). Interest is paid quarterly. The Company has pledged its interest in Prins's building as a general guarantee for its senior mortgage loan. The senior mortgage loan matures in 2020.

Longterm_debt_Details_3

Long-term debt (Details 3) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Debt and Capital Lease Obligations	$78,542		$66,013
Emer Other Financing [Member]
Debt and Capital Lease Obligations	1,129	[1]	247	[1]
Prins Other Financing [Member]
Debt and Capital Lease Obligations	1,424	[2]	0	[2]
Other Financing [Member]
Debt and Capital Lease Obligations	$93		$156
[1]	Emer other financing consists of various unsecured bank financing arrangements that carry rates of interest ranging from 1.01% to 2.90% (2013 - 1.01% to 8.00%) and are payable on maturity dates ranging from June 23, 2015 to June 23, 2017.
[2]	Prins other bank financing consists of a credit facility for maximum borrowings of €2,000. The credit facility bears interest at the 3 month Euribor + 3.5% (3.6% as of December 31, 2014). The credit facility is governed by an accounts receivable list requirement limiting such borrowings to 60% of accepted accounts receivable.

Longterm_debt_Details_4

Long-term debt (Details 4) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
2015	$522
2016	328
2017	327
2018	191
2019	26
Capital Leases, Future Minimum Payments Due	$1,394

Longterm_debt_Details_Textual

Long-term debt (Details Textual)

0 Months Ended

12 Months Ended

12 Months Ended

0 Months Ended

12 Months Ended

0 Months Ended

12 Months Ended

0 Months Ended

Jun. 27, 2014

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Jun. 27, 2014

Jun. 27, 2014

Sep. 23, 2011

Sep. 23, 2011

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Jun. 27, 2014

Jun. 27, 2014

Dec. 31, 2014

Dec. 31, 2013

Jun. 27, 2014

Jun. 27, 2014

Jun. 27, 2014

Jun. 27, 2014

Jun. 27, 2014

Jun. 27, 2014

Jun. 27, 2014

USD ($)

USD ($)

USD ($)

CAD

Emer Senior Financing [Member]

Prins Senior Financing [Member]

Prins Senior Mortgage Loan [Member]

Emer Other Financing [Member]

Prins Other Financing [Member]

Letter of Credit [Member]

Letter of Credit [Member]

Minimum [Member]

Minimum [Member]

Maximum [Member]

Maximum [Member]

Subordinated Debt [Member]

Subordinated Debt [Member]

Subordinated Debt [Member]

Subordinated Debt [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Capital Lease Obligations [Member]

Capital Lease Obligations [Member]

Capital Lease Obligations [Member]

Capital Lease Obligations [Member]

New Debentures [Member]

New Debentures [Member]

New Debentures [Member]

New Debentures [Member]

New Debentures [Member]

New Debentures [Member]

New Debentures [Member]

New Debentures [Member]

New Debentures [Member]

Amended Initial Debentures [Member]

Amended Initial Debentures [Member]

USD ($)

EUR (€)

Emer Other Financing [Member]

Emer Other Financing [Member]

Emer Other Financing [Member]

Emer Other Financing [Member]

USD ($)

CAD

USD ($)

CAD

USD ($)

EUR (€)

Minimum [Member]

Minimum [Member]

Maximum [Member]

Maximum [Member]

USD ($)

CAD

USD ($)

USD ($)

Richardson GMP Limited [Member]

Richardson GMP Limited [Member]

Richardson GMP Limited [Member]

Richardson GMP Limited [Member]

Minimum [Member]

Richardson GMP Limited [Member]

Richardson GMP Limited [Member]

USD ($)

CAD

Debt Instrument, Redemption, Period Two [Member]

Debt Instrument, Redemption, Period Three [Member]

CAD

USD ($)

CAD

Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate

9.00%

9.00%

Debt Instrument, Description of Variable Rate Basis

6-month Euribor

3-month Euribor

3-month Euribor

3 month Euribor

6-month Euribor

6-month Euribor

Debt Instrument, Basis Spread on Variable Rate

2.50%

3.50%

1.00%

3.50%

2.50%

2.50%

Debt Instrument, Interest Rate at Period End

2.70%

3.60%

1.10%

Debt Instrument, Periodic Payment, Principal

$3,891,000

$6,050,000

€ 5,000,000

Debt Instrument, Interest Rate During Period

9.00%

0.75%

0.75%

1.01%

1.01%

2.90%

8.00%

3.07%

3.07%

4.93%

7.32%

Capital Lease Obligations, Initial Lease Term

3 years

5 years

Line of Credit Facility, Maximum Borrowing Capacity before Increase

30,000,000

Proceeds from Issuance of Debt

0

0

2,450,000

17,797,000

19,000,000

33,720,000

36,000,000

51,517,000

55,000,000

10,000,000

33,720,000

36,000,000

Maximum Number Of Extension Options

six times

Embedded Derivative, Fair Value of Embedded Derivative Liability

1,169,000

1,249,000

Accretion Expense

82,000

0

Embedded Derivative, Gain (Loss) on Embedded Derivative, Net

-1,082,000

0

Debt Instrument, Term

6 months

6 months

Line of Credit Facility, Maximum Borrowing Capacity

€ 2,000,000

Percentage Of Borrowings Under Account Receivables

60.00%

Debt Instrument, Redemption, Description

The Initial Debentures were redeemable at the option of the Company at a price equal to $1,150 per $1,000 principal amount of the debentures on or before March 22, 2013

The Initial Debentures were redeemable at the option of the Company at a price equal to $1,150 per $1,000 principal amount of the debentures on or before March 22, 2013

Debentures are redeemable at the option of the Company at a price equal to $1,150 per $1,000 principal amount

debentures can be redeemed at a price equal to $1,100 per $1,000 principal amount.

Debt Instrument, Maturity Date

15-Sep-17

Debt Instrument, Maturity Date Range, Start

23-Jun-15

Debt Instrument, Maturity Date Range, End

23-Jun-17

Warranty_liability_Details

Warranty liability (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Balance, beginning of period	$28,845	$6,380	$4,401
Warranty assumed on acquisition	1,952	582	0
Warranty claims	-10,709	-5,397	-3,099
Warranty accruals	2,734	4,153	5,303
Change in estimate	0	22,837	0
Impact of foreign exchange changes	287	290	-225
Balance, end of period	23,109	28,845	6,380
Less: Current portion	-9,696	-9,955	-2,072
Long-term portion	$13,413	$18,890	$4,308

Other_longterm_liabilities_Det

Other long-term liabilities (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Severance indemnity (a)	$1,519	[1]	$1,547	[1]
Contingent consideration payable related to AFV acquisition (b)	1,240	[2]	878	[2]
Derivative Liability (note 13a)	86		0
Deferred lease inducements	0		16
Other Liabilities	2,845		2,441
Current portion (included in accounts payable and accrued liabilities, other payables)	-1,240		0
Other Liabilities, Noncurrent, Total	$1,605		$2,441
[1]	Italian law requires companies to make a mandatory termination payment to employees. It is paid, as a lump sum, when the employment ends for any reason such as retirement, resignation or layoff. The severance indemnity liability is calculated in accordance with local civil and labour laws based on each employeebs length of service, employment category and remuneration. There is no vesting period or funding requirement associated with the liability. The liability recorded in the consolidated balance sheet is the amount that the employee would be entitled to if the employee terminates immediately. This liability for severance indemnities relates primarily to the Companybs employees in Italy.
[2]	The total purchase price to acquire AFV also includes earn-out payments payable in the Companybs shares and tied to revenue and production milestones to be achieved no later than December 31, 2014. This contingent consideration has a fair value of $407 as at December 31, 2014 (December 31, 2013 - $427).The Company recorded compensation expense relating to two employees of AFV who receive earn-out payments in the Companybs shares that are tied to revenue and production milestones to be achieved no later than December 31, 2014 and contingent upon continuing employments. This contingent consideration has a fair value of $823 as at December 31, 2014 (December 31, 2013 - $451).Subsequent to year end 325,073 shares were issued to the two employees of AFV at $4.51CDN per share.

Other_longterm_liabilities_Det1

Other long-term liabilities (Details Textual)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014
	USD ($)	USD ($)	AFV [Member]
			CAD
Business Acquisition Contingent Consideration At Fair Value One	$407	$427
Business Acquisition Contingent Consideration Number of Employees	2
Business Acquisition Contingent Consideration Compensation at Fair Value	$833	$451
Shares, Issued			325,073
Shares Issued, Price Per Share			4.51

Government_assistance_Details_

Government assistance (Details Textual)	12 Months Ended				12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014	Dec. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014
	USD ($)	USD ($)	USD ($)	CAD	Industry Canada Industrial Technologies Office [Member]	Industry Canada Industrial Technologies Office [Member]	Industry Canada Industrial Technologies Office [Member]	Government of Canada Department of Natural Resources [Member]
					USD ($)	CAD	USD ($)	CAD
Research and Development Arrangement, Contract to Perform for Others, Compensation Earned	$892	$640	$842
Annual Royalties Required to be Paid under Agreement					1,164	1,350
Royalties to be Paid as Percentage of Revenue					0.33%	0.33%		1.00%
Minimum Revenue Considered for Determining Annual Royalties to be Paid under Agreement					11,638	13,500
Maximum Royalties to be Paid under Agreement					24,389	28,200		1,000
Royalty Expense					1,481		1,164
Payments for Cumulative Royalties under Agreement				8,364
Accounts Payable and Accrued Liabilities	$1,470	$1,269

Share_capital_stock_options_an2

Share capital, stock options and other stock-based plans (Details) (Employee Stock Option [Member], CAD)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Employee Stock Option [Member]
Number of shares
Outstanding , beginning of period	816,450	996,047	328,027
Granted	0	0	770,727
Exercised	-43,071	-111,986	-93,044
Forfeited/expired	-741,156	-67,611	-9,663
Outstanding, end of period	32,223	816,450	996,047
Options exercisable, end of period	32,223	305,506	226,487
Weighted average exercise price
Outstanding, beginning of period Weighted Average Exercise Price	30.2	27.78	8.96
Granted Weighted Average Exercise Price	0	0	33.77
Exercised Weighted Average Exercise Price	6.17	6.8	10.49
Forfeited/expired Weighted Average Exercise Price	33.82	33.72	33.36
Outstanding, end of period Weighted Average Exercise Price	17.64	30.2	27.78
Options exercisable, end of period Weighted Average Exercise Price	17.64	24.15	8.06

Share_capital_stock_options_an3

Share capital, stock options and other stock-based plans (Details 1) (Share units [Member], CAD)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share units [Member]
Outstanding, beginning of period (in units)	1,200,591	1,095,094	1,250,917
Granted (in units)	5,792,162	742,140	185,705
Exercised/Vested (in units)	-608,975	-448,526	-337,228
Forfeited/expired (in units)	-1,045,905	-188,117	-4,300
Outstanding, end of period (in units)	5,337,873	1,200,591	1,095,094
Units outstanding and exercisable, end of period (in units)	142,166	224,638	262,615
Outstanding, beginning of period (in Canadian dollars per share)	23.68	20.68	18.04
Granted (in Canadian dollars per share)	10.54	30.21	35.99
Exercised/Vested (in Canadian dollars per share)	19.52	24.44	19.34
Forfeited/expired (in Canadian dollars per share)	21.75	29.8	19.67
Outstanding, end of period (in Canadian dollars per share)	10.27	23.68	20.68
Units outstanding and exercisable, end of period (in Canadian dollars per share)	11.67	11.2	8.86

Share_capital_stock_options_an4

Share capital, stock options and other stock-based plans (Details 2) (CAD)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Employee Stock Option [Member]
Outstanding	0	1,337
Exercisable	0	1,337
Exercised	364	2,667
Share units [Member]
Outstanding	23,433	24,960
Exercisable	624	4,670
Exercised	7,238	18,041

Share_capital_stock_options_an5

Share capital, stock options and other stock-based plans (Details 3) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Allocated Share-based Compensation Expense	$9,683	$14,283	$12,468
Research and development
Allocated Share-based Compensation Expense	1,749	2,195	2,251
General and administrative
Allocated Share-based Compensation Expense	5,884	10,201	6,752
Sales and marketing
Allocated Share-based Compensation Expense	$2,050	$1,887	$3,465

Share_capital_stock_options_an6

Share capital, stock options and other stock-based plans (Details Textual) (USD $)	12 Months Ended			1 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jun. 28, 2013	Jun. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	8,000,000
Allocated Share-based Compensation Expense	$9,683	$14,283	$12,468
Stock Issued During Period, Value, New Issues		152,340	273,556
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs		5,065	8,126
Business Acquisition, Share Price				$30.62
BAF Technologies Inc [Member]
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares				718,485
Business Acquisition, Share Price				$33.53
Common Stock [Member]
Stock Issued During Period Shares Net Of Cancellation Upon Exercise Of Stock Options	652,046	721,186	513,490
Stock Issued During Period, Value, New Issues		152,340	273,556
Stock Issued During Period, Shares, New Issues		6,000,000	6,325,000		94,914
Share Price		$25.39	$43.25		$33.53
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs		5,065	8,126
Employee Stock Option [Member]
Allocated Share-based Compensation Expense	1,764	2,094	2,705
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate			0.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate			47.79%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate			0.38%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term			3 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Exercise Price, Ending Balance			$10.97
Share units [Member]
Allocated Share-based Compensation Expense	7,919	12,189	9,763
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate	0.00%
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Total	$30,102
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	2 years 5 months 1 day
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted	5,792,162	742,140	185,705
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Forfeitures and Expirations, Total	1,045,905	188,117	4,300
PSU's [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted	971,399	389,655
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Forfeitures and Expirations, Total	963,575	54,876
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted	4,820,763	352,485

Research_and_development_expen2

Research and development expenses (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Research and development expenses	$77,472	$91,772	$74,040
Government assistance (note 16)	-892	-640	-842
Research and development	$76,580	$91,132	$73,198

Income_taxes_Details

Income taxes (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Loss before income taxes	($150,197)	($184,537)	($97,036)
Expected income tax recovery	-39,051	-47,979	-24,259
Increase (reduction) in income taxes resulting from:
Non-deductible stock-based compensation	2,495	3,619	3,019
Other permanent differences	-446	-2,562	-2,158
Withholding taxes	969	590	1,187
Change in enacted rates	0	0	62
Foreign tax rate differences, foreign exchange and other adjustments	7,409	3,858	-382
Non-taxable income from equity investment	-3,739	-2,851	-3,308
Change in valuation allowance	25,784	37,391	27,577
Goodwill impairment	-18,543	-34,964	0
Change in uncertain tax position	1,252	0	0
Income tax expense (recovery)	($579)	$873	$1,738

Income_taxes_Details_1

Income taxes (Details 1) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Deferred income tax assets:
Net loss carry forwards	$129,258	$108,083
Intangible assets	4,091	4,276
Property, plant and equipment	6,836	5,446
Financing and share issuance costs	1,533	2,696
Warranty liability	5,131	5,726
Deferred revenue	1,416	1,191
Inventory	2,336	2,017
Research and development	2,733	2,341
Other	7,262	6,410
Total gross deferred income tax assets	160,596	138,186
Valuation allowance	-152,207	-126,424	-89,033
Total deferred income tax assets	8,389	11,762
Deferred income tax liabilities:
Intangible assets	6,386	9,884
Property, plant and equipment	2,754	3,132
Other	774	650
Total deferred income tax liabilities	9,914	13,666
Total net deferred income tax liabilities	1,525	1,904
Allocated as follows:
Current deferred income tax assets	3,556	3,109
Current deferred income tax liabilities	-398	-468
Long-term deferred income tax assets	271	379
Long-term deferred income tax liabilities	-4,954	-4,903
Total net deferred income tax liabilities	($1,525)	($1,904)

Income_taxes_Details_2

Income taxes (Details 2) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Beginning balance	$126,424	$89,033
Additions	25,783	37,391
Reductions	0	0
Ending valuation allowance	$152,207	$126,424

Income_taxes_Details_3

Income taxes (Details 3) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net income (loss) before income taxes	($150,197)	($184,537)	($97,036)
Current	606	1,414	2,147
Deferred	-1,185	-541	-409
Total	-579	873	1,738
CANADA
Net income (loss) before income taxes	-87,783	-99,188	-93,688
Current	165	444	1,339
Deferred	301	89	53
Total	466	533	1,392
UNITED STATES
Net income (loss) before income taxes	-49,577	-31,019	-1,589
Current	8	56	-62
Deferred	0	-295	0
Total	8	-239	-62
ITALY
Net income (loss) before income taxes	-3,834	-27,247	-318
Current	521	836	775
Deferred	-1,463	-311	25
Total	-942	525	800
Other [Member]
Net income (loss) before income taxes	-9,003	-27,083	-1,441
Current	-88	78	95
Deferred	-23	-24	-487
Total	($111)	$54	($392)

Income_taxes_Details_4

Income taxes (Details 4) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Operating Loss Carryforwards	$478,693,116
Expiring in 2015 [Member]
Operating Loss Carryforwards	0
Expiring in 2016 [Member]
Operating Loss Carryforwards	0
Expiring in 2017 [Member]
Operating Loss Carryforwards	0
Expiring In 2018 [Member]
Operating Loss Carryforwards	1,085,596
Expiring in 2019 [Member]
Operating Loss Carryforwards	6,725,731
Expiring in 2020 and Later [Member]
Operating Loss Carryforwards	470,881,789
CANADA
Operating Loss Carryforwards	387,553,717
CANADA | Expiring in 2015 [Member]
Operating Loss Carryforwards	0
CANADA | Expiring in 2016 [Member]
Operating Loss Carryforwards	0
CANADA | Expiring in 2017 [Member]
Operating Loss Carryforwards	0
CANADA | Expiring In 2018 [Member]
Operating Loss Carryforwards	0
CANADA | Expiring in 2019 [Member]
Operating Loss Carryforwards	0
CANADA | Expiring in 2020 and Later [Member]
Operating Loss Carryforwards	387,553,717
ITALY
Operating Loss Carryforwards	6,429,576
ITALY | Expiring in 2015 [Member]
Operating Loss Carryforwards	0
ITALY | Expiring in 2016 [Member]
Operating Loss Carryforwards	0
ITALY | Expiring in 2017 [Member]
Operating Loss Carryforwards	0
ITALY | Expiring In 2018 [Member]
Operating Loss Carryforwards	0
ITALY | Expiring in 2019 [Member]
Operating Loss Carryforwards	0
ITALY | Expiring in 2020 and Later [Member]
Operating Loss Carryforwards	6,429,576
UNITED STATES
Operating Loss Carryforwards	55,353,513
UNITED STATES | Expiring in 2015 [Member]
Operating Loss Carryforwards	0
UNITED STATES | Expiring in 2016 [Member]
Operating Loss Carryforwards	0
UNITED STATES | Expiring in 2017 [Member]
Operating Loss Carryforwards	0
UNITED STATES | Expiring In 2018 [Member]
Operating Loss Carryforwards	0
UNITED STATES | Expiring in 2019 [Member]
Operating Loss Carryforwards	0
UNITED STATES | Expiring in 2020 and Later [Member]
Operating Loss Carryforwards	55,353,513
SWEDEN
Operating Loss Carryforwards	13,710,864
SWEDEN | Expiring in 2015 [Member]
Operating Loss Carryforwards	0
SWEDEN | Expiring in 2016 [Member]
Operating Loss Carryforwards	0
SWEDEN | Expiring in 2017 [Member]
Operating Loss Carryforwards	0
SWEDEN | Expiring In 2018 [Member]
Operating Loss Carryforwards	0
SWEDEN | Expiring in 2019 [Member]
Operating Loss Carryforwards	0
SWEDEN | Expiring in 2020 and Later [Member]
Operating Loss Carryforwards	13,710,864
Other Jurisdictions [Member]
Operating Loss Carryforwards	15,645,446
Other Jurisdictions [Member] | Expiring in 2015 [Member]
Operating Loss Carryforwards	0
Other Jurisdictions [Member] | Expiring in 2016 [Member]
Operating Loss Carryforwards	0
Other Jurisdictions [Member] | Expiring in 2017 [Member]
Operating Loss Carryforwards	0
Other Jurisdictions [Member] | Expiring In 2018 [Member]
Operating Loss Carryforwards	1,085,596
Other Jurisdictions [Member] | Expiring in 2019 [Member]
Operating Loss Carryforwards	6,725,731
Other Jurisdictions [Member] | Expiring in 2020 and Later [Member]
Operating Loss Carryforwards	$7,834,119

Income_taxes_Details_5

Income taxes (Details 5) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014
Beginning Balance	$0
Tax positions related to the current year:
Additions	0
Reductions	0
Incease Decrease related to the tax posiion current year	0
Tax positions related to prior years:
Additions	1,230
Reductions	0
Settlements	0
Lapses in statutes of limitations	0
Ending Balance	$1,230

Income_taxes_Details_Textual

Income taxes (Details Textual) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	26.00%	26.00%	25.00%
Unrecognized Tax Benefits	$1,230	$0

Related_party_transactions_Det

Related party transactions (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Expenses incurred in transactions with related party	$6,486	$6,254	$6,464
Research and development [Member]
Expenses incurred in transactions with related party	3	178	160
General and administrative [Member]
Expenses incurred in transactions with related party	1,548	1,351	2,621
Sales and marketing [Member]
Expenses incurred in transactions with related party	$4,935	$4,725	$3,683

Related_party_transactions_Det1

Related party transactions (Details Textual) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Due from Related Parties	$2,538	$3,621
Related Party Transaction, Expenses from Transactions with Related Party	6,486	6,254	6,464
Interest Expense [Member]
Related Party Transaction, Expenses from Transactions with Related Party	$0	$0	$114

Service_and_other_revenue_Deta

Service and other revenue (Details Textual) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
License and Services Revenue	$0	$0	$7,923
Sales Revenue, Services, Other	1,480	1,484	1,414
Service Revenue Recognized On Achievements Of Certain Milestones	$11,074	$14,547	$13,907

Commitments_and_contingencies_1

Commitments and contingencies (Details) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
2015	$3,946
2016	4,978
2017	5,890
2018	4,969
2019	4,960
Thereafter	33,125
Operating Leases, Future Minimum Payments Due	$57,868

Commitments_and_contingencies_2

Commitments and contingencies (Details Textual) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating Leases, Rent Expense, Net, Total	$3,879	$5,675	$4,492
Guarantor Obligations, Current Carrying Value	298	342
Provision For Inventory Purchase Commitment	$4,106	$0	$0

Segmented_information_Details

Segmented information (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Total segment revenues	$1,086,268	$941,263	$625,727
Less: equity investees' revenue	-955,699	-777,231	-470,101
Total consolidated revenues	130,569	164,032	155,626
Total segment operating loss	-9,685	-112,937	-49,848
Less: equity investeesb operating income	-100,057	-38,035	-45,133
Net consolidated operating income (loss) excluding depreciation and amortization, losses on impairments, write-downs and disposals, provision for inventory purchase commitments, foreign exchange loss (gain), bank charges and other:	-109,742	-150,972	-94,981
Depreciation and amortization:	18,666	16,288	11,395
Provision for inventory purchase commitments (On-Road Systems)	4,106	0	0
Losses on impairments, write-downs and disposals	52,376	57,811	11,395
Net consolidated operating loss excluding depreciation and amortization, losses on impairments, write-downs and disposals, provision for inventory purchase commitments, foreign exchange (gain) loss, bank charges and other:	-162,118	-208,783	-106,376
Foreign exchange (gain) loss, bank charges and other	-2,731	-14,573	1,922
Loss from operations	-159,387	-194,210	-108,298
Interest on long-term debt and other income (expenses), net	-5,032	-3,771	-4,928
Income from investment accounted for by the equity method	14,222	13,444	16,190
Loss before income taxes	-150,197	-184,537	-97,036
Applied Technologies [Member]
Total segment revenues	86,168	93,216	91,675
Total segment operating loss	-5,204	6,635	9,820
Depreciation and amortization:	8,012	7,838	7,905
On-Road Systems [Member]
Total segment revenues	37,031	55,090	37,558
Total segment operating loss	-14,431	-59,843	-40,937
Depreciation and amortization:	5,561	3,186	1,028
Losses on impairments, write-downs and disposals	26,146	9,959	0
Off-Road Systems [Member]
Total segment revenues	3,789	3,309	3,149
Total segment operating loss	-2,744	-14,218	-13,653
Depreciation and amortization:	0	450	83
Cummins Westport Inc [Member]
Total segment revenues	337,234	310,651	198,015
Total segment operating loss	21,555	23,539	35,368
Corporate And Technology Investments [Member]
Total segment revenues	3,581	12,417	23,244
Total segment operating loss	-87,363	-83,546	-50,211
Depreciation and amortization:	5,093	4,814	2,379
Losses on impairments, write-downs and disposals	3,458	31,564	0
Weichai Westport Inc [Member]
Total segment revenues	618,465	466,580	272,086
Total segment operating loss	$78,502	$14,496	$9,765

Segmented_information_Details_

Segmented information (Details 1) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Total additions to long-lived assets excluding business combinations	$10,249	$26,450	$31,352
Applied Technologies [Member]
Total additions to long-lived assets excluding business combinations	938	4,408	3,000
On-Road Systems [Member]
Total additions to long-lived assets excluding business combinations	1,340	15,555	10,306
Off-Road Systems [Member]
Total additions to long-lived assets excluding business combinations	0	908	1,481
Corporate And Technology Investments [Member]
Total additions to long-lived assets excluding business combinations	$7,971	$5,579	$16,565

Segmented_information_Details_1

Segmented information (Details 2)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Americas including United States [Member]
Concentration Risk, Percentage	40.00%	42.00%	38.00%
Asia including China [Member]
Concentration Risk, Percentage	12.00%	11.00%	9.00%
Other including Italy [Member]
Concentration Risk, Percentage	48.00%	47.00%	53.00%

Recovered_Sheet1

Segmented Information (Details 3) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Assets Excluding Equity Investees Total Assets	$692,851	$738,160
Less: equity investees' total assets	355,156	246,489
Total consolidated assets	337,695	491,671
Applied Technologies [Member]
Assets Excluding Equity Investees Total Assets	151,428	144,803
On-Road Systems [Member]
Assets Excluding Equity Investees Total Assets	130,461	111,323
Off-Road Systems [Member]
Assets Excluding Equity Investees Total Assets	1,042	6,564
Corporate and Technology Investments and unallocated assets [Member]
Assets Excluding Equity Investees Total Assets	54,764	228,981
Cummins Westport Inc [Member]
Assets Excluding Equity Investees Total Assets	172,941	115,343
Weichai Westport Inc [Member]
Assets Excluding Equity Investees Total Assets	$182,215	$131,146

Segmented_information_Details_2

Segmented information (Details 4) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Capital Assets and Goodwill Excluding Equity Investees Long Lived Assets	$116,436	$155,310
Less: equity investeesb long-lived assets	7,030	8,117
Total consolidated long-lived assets	109,406	147,193
ITALY
Capital Assets and Goodwill Excluding Equity Investees Long Lived Assets	53,319	66,918
NETHERLANDS
Capital Assets and Goodwill Excluding Equity Investees Long Lived Assets	9,944	0
CANADA
Capital Assets and Goodwill Excluding Equity Investees Long Lived Assets	25,083	30,713
UNITED STATES
Capital Assets and Goodwill Excluding Equity Investees Long Lived Assets	20,320	47,322
SWEDEN
Capital Assets and Goodwill Excluding Equity Investees Long Lived Assets	208	322
CHINA
Capital Assets and Goodwill Excluding Equity Investees Long Lived Assets	6,329	8,675
AUSTRALIA
Capital Assets and Goodwill Excluding Equity Investees Long Lived Assets	$1,233	$1,360

Segmented_information_Details_3

Segmented information (Details Textual) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Goodwill	$23,352	$41,500	$56,879
Long-term Investments, Total	33,324	22,128
Applied Technologies [Member]
Goodwill	23,352	22,958
Long-term Investments, Total	426	256
On-Road Systems [Member]
Goodwill	0	18,542
Corporate And Technology Investments [Member]
Long-term Investments, Total	$32,898	$21,872

Financial_instruments_Details

Financial instruments (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014
Carrying amount	$135,338
Contractual cash flows	231,842
Contractual Obligation, Due in Next Twelve Months	73,867
Contractual Obligation, Due in Second and Third Year	98,783
Contractual Obligation, Due in Fourth and Fifth Year	13,356
Contractual Obligation, Due after Fifth Year	45,838
Capital Lease Obligations [Member]
Carrying amount	1,394
Contractual cash flows	1,490
Contractual Obligation, Due in Next Twelve Months	626
Contractual Obligation, Due in Second and Third Year	665
Contractual Obligation, Due in Fourth and Fifth Year	200
Contractual Obligation, Due after Fifth Year	0
Unsecured subordinated debentures [Member]
Carrying amount	46,491	[1]
Contractual cash flows	68,613	[1]
Contractual Obligation, Due in Next Twelve Months	4,950	[1]
Contractual Obligation, Due in Second and Third Year	63,663	[1]
Contractual Obligation, Due in Fourth and Fifth Year	0	[1]
Contractual Obligation, Due after Fifth Year	0	[1]
Senior financing [Member]
Carrying amount	15,910	[2]
Contractual cash flows	16,565	[2]
Contractual Obligation, Due in Next Twelve Months	6,314	[2]
Contractual Obligation, Due in Second and Third Year	8,353	[2]
Contractual Obligation, Due in Fourth and Fifth Year	779	[2]
Contractual Obligation, Due after Fifth Year	1,120	[2]
Senior revolving financing [Member]
Carrying amount	12,101	[3]
Contractual cash flows	12,743	[3]
Contractual Obligation, Due in Next Twelve Months	315	[3]
Contractual Obligation, Due in Second and Third Year	12,429	[3]
Contractual Obligation, Due in Fourth and Fifth Year	0	[3]
Contractual Obligation, Due after Fifth Year	0	[3]
Other bank financing [Member]
Carrying amount	2,646	[4]
Contractual cash flows	3,135	[4]
Contractual Obligation, Due in Next Twelve Months	1,050	[4]
Contractual Obligation, Due in Second and Third Year	478	[4]
Contractual Obligation, Due in Fourth and Fifth Year	121	[4]
Contractual Obligation, Due after Fifth Year	1,485	[4]
Operating lease commitments [Member]
Carrying amount	0
Contractual cash flows	57,867
Contractual Obligation, Due in Next Twelve Months	3,946
Contractual Obligation, Due in Second and Third Year	10,868
Contractual Obligation, Due in Fourth and Fifth Year	9,929
Contractual Obligation, Due after Fifth Year	33,125
Royalty payments [Member]
Carrying amount	1,294	[5]
Contractual cash flows	15,927	[5]
Contractual Obligation, Due in Next Twelve Months	1,164	[5]
Contractual Obligation, Due in Second and Third Year	2,327	[5]
Contractual Obligation, Due in Fourth and Fifth Year	2,327	[5]
Contractual Obligation, Due after Fifth Year	10,108	[5]
Accounts Payable and Accrued Liabilities [Member]
Carrying amount	55,502
Contractual cash flows	55,502
Contractual Obligation, Due in Next Twelve Months	55,502
Contractual Obligation, Due in Second and Third Year	0
Contractual Obligation, Due in Fourth and Fifth Year	0
Contractual Obligation, Due after Fifth Year	$0
[1]	Includes interest at 9%.
[2]	Includes interest at rates disclosed in note 13(b) in effect at December 31, 2014.
[3]	Includes interest at rates disclosed in note 13(c) in effect at December 31, 2014.
[4]	Includes interest at rates disclosed in note 13(d) in effect at December 31, 2014.
[5]	From fiscal 2011 to 2015 inclusive, the Company is obligated to pay annual royalties equal to the greater of $1,164 (CDN$1,350) or 0.33% of the Company's gross annual revenue from all sources, provided that gross revenue exceeds $12,693 (CDN$13,500) in any aforementioned fiscal year, up to a maximum of $26,514 (CDN$28,189). The Company has assumed the minimum required payments.

Financial_instruments_Details_

Financial instruments (Details 1)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2014	Dec. 31, 2014
In Thousands, unless otherwise specified	USD ($)	USD ($)	USD ($)	USD ($)	United States of America, Dollars	Euro Member Countries, Euro
					USD ($)	EUR (€)
Cash and cash equivalents	$93,282	$178,513	$188,958	$63,285	$69,899	€ 9,190
Short-term investments	723	32,091			500
Accounts receivable	46,849	59,315			14,304	38,916
Accounts payable	$55,502	$54,792			$4,012	€ 27,667

Financial_instruments_Details_1

Financial instruments (Details Textual)

12 Months Ended

12 Months Ended

12 Months Ended

In Thousands, unless otherwise specified

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

USD ($)

EUR (€)

USD ($)

Accounts Receivable [Member]

Accounts Receivable [Member]

Accounts Receivable [Member]

Accounts Receivable [Member]

Accounts Receivable [Member]

Accounts Receivable [Member]

Maximum [Member]

Minimum [Member]

Royalty payments [Member]

Royalty payments [Member]

Royalty payments [Member]

Royalty payments [Member]

Customer Receivable [Member]

Customer Receivable [Member]

Government Grants, Receivable [Member]

Government Grants, Receivable [Member]

Due from Partners and Indirect and Value Added Taxes Receivable [Member]

Due from Partners and Indirect and Value Added Taxes Receivable [Member]

Maximum [Member]

Maximum [Member]

Minimum [Member]

Minimum [Member]

Credit Concentration Risk [Member]

Credit Concentration Risk [Member]

Credit Concentration Risk [Member]

Credit Concentration Risk [Member]

Credit Concentration Risk [Member]

Credit Concentration Risk [Member]

USD ($)

CAD

USD ($)

CAD

Cash And Cash Equivalents, Short-Term Investments And Accounts Receivable

$140,854

$269,919

Cash, Cash Equivalents, and Short-term Investments, Total

94,005

Royalty Guarantees, Commitments, Amount

1,164

1,350

Contractual Obligations, Annual Royalty Payments as Percentage of Gross Revenue, Option Two

0.33%

0.33%

Contractual Obligation, Revenue for Payment of Royalty

12,693

13,500

Contractual Obligations, Annual Royalty Payments

26,514

28,189

Concentration Risk, Percentage

87.00%

88.00%

1.00%

1.00%

12.00%

11.00%

Accounts Receivable, Credit Period

30 days

90 days

Interest Rate Risk, Effect of Change in Exchange Rate by Fifty Basis Point on US Dollar Denominated, Financial Instruments

52

Foreign Currency Risk Effect Of Change In Exchange Rate By Twenty Five Basis Point On Euro Denominated Financial Instruments

51

Foreign Currency Risk Effect Of Change In Exchange Rate By Twenty Five Basis Point On US Dollar Denominated Financial Instruments

$201

Debt Instrument, Interest Rate During Period

9.00%

9.00%