Westport Fuel Systems (WPRT) 40-F27 Feb 142013 FY Annual report (Canada)Financial data

Company Profile

Document_And_Entity_Informatio

Document And Entity Information	12 Months Ended
Document And Entity Information	Dec. 31, 2013
Document Information [Line Items]	'
Entity Registrant Name	'WESTPORT INNOVATIONS INC
Entity Central Index Key	'0001370416
Document Type	'40-F
Document Period End Date	31-Dec-13
Amendment Flag	'false
Current Fiscal Year End Date	'--12-31
Entity Current Reporting Status	'Yes
Entity Common Stock, Shares Outstanding	62,733,762
Document Fiscal Year Focus	'2013
Document Fiscal Period Focus	'FY

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Assets	'	'
Cash and cash equivalents	$178,513	$188,958
Short-term investments	32,091	26,902
Accounts receivable (note 5)	59,315	44,189
Inventories (note 6)	40,626	44,946
Prepaid expenses	6,072	6,641
Current portion of deferred income tax assets (note 20(b))	3,109	7,183
Total current assets	319,726	318,819
Long-term investments (note 7)	22,128	19,118
Other assets	2,245	1,852
Property, plant and equipment (note 9)	67,349	58,194
Intangible assets (note 10)	38,344	35,215
Deferred income tax assets (note 20(b))	379	0
Goodwill (note 11)	41,500	56,879
Total assets	491,671	490,077
Liabilities and Shareholders' Equity	'	'
Accounts payable and accrued liabilities (note 12)	54,792	48,509
Current portion of deferred revenue	6,727	1,254
Current portion of deferred income tax liabilities (note 20(b))	468	65
Current portion of long-term debt (note 13)	53,025	28,566
Current portion of warranty liability (note 14)	9,955	2,072
Total current liabilities	124,967	80,466
Warranty liability (note 14)	18,890	4,308
Long-term debt (note 13)	12,988	52,156
Deferred revenue	4,580	5,215
Deferred income tax liabilities (note 20(b))	4,903	9,245
Other long-term liabilities (note 15)	2,441	2,606
Total liabilities	168,769	153,996
Shareholdersâ€™ equity:	'	'
Authorized: Unlimited common shares, no par value Unlimited preferred shares in series, no par value Issued:62,733,762 (2012 - 55,294,091) common shares	916,497	733,385
Other equity instruments	13,834	9,228
Additional paid in capital	8,205	6,384
Accumulated deficit	-615,342	-429,932
Accumulated other comprehensive income	-292	17,016
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	322,902	336,081
Commitments and contingencies (note 16 and 23)	'	'
Total liabilities and shareholders' equity	$491,671	$490,077

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets [Parenthetical] (USD $)	Dec. 31, 2013	Dec. 31, 2012
Common Stock, No Par Value	$0	$0
Preferred Stock, No Par Value	$0	$0
Common shares, shares issued (in shares)	62,733,762	55,294,091

Consolidated_Statements_of_Ope

Consolidated Statements of Operations and Comprehensive Income (Loss) (USD $)	9 Months Ended	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
Product revenue	$75,164	$134,171	$128,914
Parts revenue	2,351	13,830	3,468
Service and other revenue (note 22)	10,181	16,031	23,244
Revenue, Net	87,696	164,032	155,626
Cost of revenue and expenses:	'	'	'
Cost of product and parts revenue	67,093	148,690	102,486
Research and development (note 18(d) and 19)	36,574	91,132	73,198
General and administrative (note 18(d))	22,738	46,475	44,811
Sales and marketing (note 18(d))	15,302	28,707	30,112
Foreign exchange (gain) loss	-2,053	-15,168	1,185
Depreciation and amortization	6,200	16,288	11,395
Bank charges, interest and other	917	595	737
Loss on disposal of assets	0	4,838	0
Intangible impairment (note 10)	0	1,721	0
Goodwill impairment (note 11)	0	34,964	0
Cost of Revenue	146,771	358,242	263,924
Loss before undernoted	-59,075	-194,210	-108,298
Income from investments accounted for by the equity method	14,458	13,444	16,190
Interest on long-term debt and amortization of discount	-2,998	-4,789	-5,354
Interest and other income	661	1,018	426
Loss before income taxes	-46,954	-184,537	-97,036
Income tax expense (recovery) (note 20):	'	'	'
Current	1,028	1,414	2,147
Deferred	-2,188	-541	-409
Income Tax Expense (Benefit)	-1,160	873	1,738
Net loss for the period	-45,794	-185,410	-98,774
Other comprehensive income (loss):	'	'	'
Cumulative translation adjustment	-12,370	-17,308	3,745
Comprehensive loss	($58,164)	($202,718)	($95,029)
Loss per share:	'	'	'
Basic and diluted (in dollars per share)	($0.96)	($3.22)	($1.83)
Weighted average common shares outstanding:	'	'	'
Basic and diluted (in shares)	47,933,348	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	Total	Share capital [Member]	Other equity instruments [Member]	Additional paid in capital [Member]	Accumulated deficit [Member]	Accumulated other comprehensive income [Member]
Balance at Mar. 31, 2011	$181,086	$430,608	$4,205	$5,141	($284,509)	$25,641
Balance (in shares) at Mar. 31, 2011	'	46,972,304	'	'	'	'
Issue of common shares on exercise of stock options	1,816	2,810	0	-994	0	0
Issue of common shares on exercise of stock options (in shares)	'	225,845	'	'	'	'
Issue of common shares on exercise of performance share units	0	3,799	-3,799	0	0	0
Issue of common shares on exercise of performance share units (in shares)	'	391,612	'	'	'	'
Issue of common shares in connection with acquisitions	23,052	23,052	0	0	0	0
Issue of common shares in connection with acquisition (in shares)	'	915,021	'	'	'	'
Cancellation of common shares	-1,258	-403	0	0	-855	0
Cancellation of common shares (in shares)	'	-49,181	'	'	'	'
Stock-based compensation	6,058	0	5,706	352	0	0
Net loss for the year	-45,794	0	0	0	-45,794	0
Other comprehensive income (loss)	-12,370	0	0	0	0	-12,370
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 performance share units	0	6,597	-6,597	0	0	0
Issue of common shares on exercise of performance share units (in shares)	'	420,446	'	'	'	'
Issue of common shares in connection with acquisitions	0	'	'	'	'	'
Cancellation of common shares	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
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
Other comprehensive income (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 performance share units	0	10,599	-10,599	0	0	0
Issue of common shares on exercise of performance share units (in shares)	'	609,200	'	'	'	'
Issue of common shares in connection with acquisitions	24,091	24,091	0	0	0	0
Issue of common shares in connection with acquisition (in shares)	'	718,485	'	'	'	'
Cancellation of common shares	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
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
Other comprehensive income (loss)	-17,308	0	0	0	0	-17,308
Acquisition to be settled by issuance of common shares	3,285	0	3,285	0	0	0
Acquisition to be settled by issuance of common shares (in shares)	'	0	'	'	'	'
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	'	'	'	'

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
Cash flows from operating activities:	'	'	'
Loss for the period	($45,794)	($185,410)	($98,774)
Items not involving cash:	'	'	'
Depreciation and amortization	6,200	16,288	11,395
Stock-based compensation expense	6,179	14,283	12,468
Unrealized foreign exchange gain	-2,053	-15,168	1,185
Deferred income tax expense (recovery)	-2,188	-541	-409
Income from investments accounted for by the equity method	-14,458	-13,444	-16,190
Accretion of long-term debt	1,016	1,643	2,094
Loss on disposal of assets	0	4,838	0
Inventory obsolescence and write-downs	0	4,925	0
Intangible impairment	0	1,721	0
Goodwill impairment	0	34,964	0
Other	607	-37	340
Changes in non-cash operating working capital:	'	'	'
Accounts receivable	-14,598	-12,289	6,733
Inventories	-2,051	5,179	-7,920
Prepaid expenses	-4,649	513	179
Accounts payable and accrued liabilities	-857	-2,064	-742
Deferred revenue	1,561	5,208	3,115
Warranty liability	2,751	22,602	1,979
Net cash provided by operating activities	-68,334	-116,789	-84,547
Cash flows from investing activities:	'	'	'
Purchase of property, plant and equipment	-13,123	-26,450	-30,363
Purchase of intangible assets	-123	0	-989
(Purchase) sale of short-term investments, net	26,621	-5,771	-22,520
Repayment of loan receivable	0	0	2,494
Increase loan payable	29,080	0	2,450
Repayment of loan payable	-23,840	0	-21,840
Acquisitions, net of acquired cash (note 4)	-9,084	1,178	-1,125
Investment in equity interest (note 7(a))	-955	0	0
Dividends received from joint ventures	10,000	8,287	22,600
Net cash used in investing activities	18,576	-22,756	-49,293
Cash flows from financing activities:	'	'	'
Increase in operating lines of credit	0	0	4,245
Repayment of operating lines of credit	-3,240	-3,731	-3,118
Repayment of long-term debt	-53,278	-9,947	-6,725
Issuance of subordinated debenture notes	34,345	0	0
Finance costs incurred	-1,392	0	0
Proceeds from stock options exercised	1,816	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	-21,749	134,338	260,801
Effect of foreign exchange on cash and cash equivalents	3,259	-5,238	-1,288
(Decrease) increase in cash and cash equivalents	-68,248	-10,445	125,673
Cash and cash equivalents, beginning of period	131,533	188,958	63,285
Cash and cash equivalents, end of period	63,285	178,513	188,958
Supplementary information:	'	'	'
Interest paid	1,349	3,911	3,532
Taxes paid, net of refunds	1,472	1,321	1,982
Non-cash transactions:	'	'	'
Shares issued on exercise of performance share units	3,799	10,599	6,597
Cancellation of performance share units	1,258	0	0
Common shares issued in connection with acquisitions (note 4)	23,052	24,091	0
Acquisition to be settled by issuance of common shares (note 4(a))	0	3,285	0
Contingent consideration payable in common shares in connection with acquisitions (note 4(c))	$428	$0	$0

Company_organization_and_opera

Company organization and operations	12 Months Ended
	Dec. 31, 2013
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, 2013

Accounting Policies [Abstract]

Organization, Consolidation and Presentation of Financial Statements Disclosure and Significant Accounting Policies [Text Block]

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 (“U.S. GAAP”).

(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, 2013

December 31, 2012

December 31, 2013

December 31, 2012

Canadian dollar

0.94

1.01

0.97

Australian dollar

0.89

1.04

0.97

1.04

Euro

1.38

1.32

1.33

1.29

RMB

0.17

0.16

Swedish Krona

0.16

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:

Accounts receivable are measured at amortized cost. An allowance for doubtful accounts is recorded based on a review of specific accounts deemed uncollectible. Account balances are charged against the allowance in the period in which it is considered probable that the receivable will not be recovered.

(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. An inventory obsolescence provision is provided to the extent cost of inventory exceeds net realizable value. In establishing the amount of the inventory obsolescence provision, management estimates the likelihood that inventory carrying values will be affected by changes in market demand and technology, which would make inventory on hand obsolete.

(g)

Property, plant and equipment:

Property, plant and equipment are stated at cost. Depreciation is provided as follows:

Assets

Basis

Rate

Buildings

Straight-line

10 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 for 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, including property, plant and equipment, and intellectual property, to be held and used 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, including 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 together with known information 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 two-year 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 and parts revenue is recognized when the products are shipped and title passes to the customer.

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.

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 of 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 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.

When an arrangement includes multiple deliverables, the Company allocates the consideration to each separate deliverable (unit of accounting) based on relative selling prices. A separate unit of accounting is identified if the delivered item(s) have standalone value and the delivery or performance of undelivered items is considered probable and within the control of the Company. Revenue for each unit of account is recognized in accordance with the above revenue recognition principles.

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 uses the asset and liability method of accounting for income taxes. Under this method, deferred income tax assets and liabilities are determined based on temporary differences between the accounting and tax basis of the assets and liabilities and for loss carry forwards and are measured using the tax rates expected to apply when these tax assets and liabilities are recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rate is recognized in income in the period that includes income tax laws that have been enacted at the balance sheet date. A valuation allowance is provided to reduce the deferred income tax assets if, based upon available evidence, it is more-likely-than-not that some or all of the deferred income tax assets will not be realized.

Tax credits, including investment tax credits and research and development credits, are recognized in income tax expense in the same year in which the related expenditures are charged to earnings or loss, provided there is reasonable assurance the benefits will be realized.

Accounting_changes

Accounting changes	12 Months Ended
	Dec. 31, 2013
Accounting Changes and Error Corrections [Abstract]	'
Accounting Changes and Error Corrections [Text Block]	'
		3	Accounting changes:

		(a)	Adoption of new accounting standards:

	Balance sheet:

	In December 2011, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Updated (“ASU”) No. 2011-11, Balance Sheet (Topic 210): Disclosures about Offsetting Assets and Liabilities (“ASU 2011-11”). ASU 2011-11 enhances disclosures regarding financial instruments and derivative instruments. Entities are required to provide both net information and gross information for these assets and liabilities in order to enhance comparability between those entities that prepare their financial statements on the basis of U.S. GAAP and those entities that prepare their financial statements on the basis of International Financial Reporting Standards (“IFRS”). In January 2013, the FASB issued ASU No. 2013-01 (“ASU 2013-01”), to clarify the scope of the new offsetting disclosures in ASU 2011-11. The ASU clarifies that the scope includes bifurcated embedded derivatives, repurchase agreements and reverse repurchase agreements, and securities borrowing and lending agreements subject to a master netting arrangement or similar agreements. These updates were effective for the Company on January 1, 2013. The adoption of the updates did not have a material impact on the Company’s consolidated financial statements.

	Comprehensive Income:

	In February 2013, the FASB issued ASU No. 2013-02, Comprehensive Income (Topic 220): Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income (“ASU 2013-02”). ASU 2013-02 improves the reporting of reclassifications out of accumulated other comprehensive income. Entities are required to report the effect of significant reclassifications out of accumulated other comprehensive income on the respective line items in net income if the amount being reclassified is required under U.S. GAAP to be reclassified in its entirety to net income. For other amounts that are not required under U.S. GAAP to be reclassified in their entirety to net income in the same reporting period, an entity is required to cross-reference other disclosures required under U.S. GAAP that provide additional detail about those amounts. This update was effective for the Company on January 1, 2013. The adoption of this update did not have a material impact on the Company’s consolidated financial statements.

		(b)	New accounting pronouncements:

	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 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, 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 is to be applied prospectively effective on January 1, 2014. The Company anticipates that the adoption of this standard will not have a material impact on the Company’s consolidated financial statements.

Business_combinations

Business combinations	12 Months Ended
Business combinations	Dec. 31, 2013
Business Combinations [Abstract]	'
Business Combination Disclosure [Text Block]	'
	4	Business combinations:

		(a)	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. The revenue and expenses of BAF for the three days, June 28 – June 30, 2013, of the reporting period during which BAF was a part of the Company are immaterial. 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, will be issuable to Clean Energy 12 months after the acquisition date. 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). The Holdback shares have been recognized in “Other equity instruments”.

	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 is 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 consideration of the consideration payable of $5,000 and the fair value of the goods and services to be recognized 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.

			Assigned fair value			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 difference between the provisional allocation reported in the Company’s interim financial statements subsequent to the acquisition date and the final allocation of goodwill is primarily due to finalizing the valuation of intangible assets and the amount allocated to deferred income tax liabilities.

	Pro forma results

	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.

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.

	(b)	Acquisition of Advanced Engine Components Limited (“AEC”):

On March 20, 2012, the Company acquired, through its wholly owned subsidiary, Westport Innovations (Australia) Pty Ltd., certain assets of AEC. Based in Perth, Australia, AEC specializes in research, development, and production of patented electronic fuel injection and engine management technologies that enable vehicle engines to operate on natural gas.

The fair value of the assets acquired and liabilities assumed are as follows:

Consideration allocated to:
Total tangible assets		$	685
Intangible assets subject to amortization over 8 years			832

Total assets acquired			1,517
Less: total liabilities			-392

Total net assets acquired		$	1,125

The Company paid cash totaling $1,125 (AUD$1,082) for the acquisition. The Company also assumed AEC's Australian leased facility and approximately ten of AEC's employees. The acquisition was accounted for as a business combination using the acquisition method.

The foreign exchange rate used to translate Australian dollar denominated assets acquired, liabilities assumed and purchase consideration into U.S. dollars was 1.04 based on the March 20, 2012 closing rate.

The Company incurred acquisition related expenses of $280 during the year ended December 31, 2012, which have been recorded in General and Administrative expenses in the consolidated statement of operations.

The Company has determined that the acquisition of AEC was a non-material business combination. As such, pro forma disclosures are not required.

	(c)	Acquisition of Alternative Fuel Vehicle Sweden AB (“AFV”):

On October 11, 2011, the Company acquired, through its wholly owned subsidiary Westport Light Duty Canada Inc., 100% of the outstanding shares of AFV. The fair value of the consideration for the acquisition was $3,939. Westport paid cash of $2,558 on closing and issued 33,161 common shares with a value of $953 based on the TSX closing price of the Company’s shares on October 11, 2011 of $28.74 (CDN$29.56). There is also a contingent earn-out, which will be settled in Westport shares if AFV achieves certain performance targets by December 31, 2014.

The Company also assumed approximately $1,087 in existing debt of AFV. Upon closing, Westport settled $420 of the debt, leaving approximately $667 in debt on the consolidated balance sheet as of October 11, 2011.

The acquisition was accounted for as a business combination using the acquisition method. The results of AFV have been included in the consolidated financial statements of the Company from October 11, 2011.

The fair value of the assets acquired and liabilities assumed are as follows:

Consideration allocated to:
Total tangible assets, including cash of $8		$	2,161
Intangible assets subject to amortization over 8 years			2,638
Goodwill			2,701

Total assets acquired			7,500
Less: total liabilities			-3,561

Total net assets acquired		$	3,939

Consideration:
Cash		$	2,558
Common shares			953
Contingent consideration payable			428

		$	3,939

The foreign exchange rate used to translate assets acquired, liabilities assumed and purchase consideration from Swedish Krona into U.S. dollars was 6.6712 based on the October 11, 2011 closing rate.

The Company recognized goodwill associated with the transaction of $2,701. Goodwill includes the value of the assembled work force and expected synergies including access to markets and product know-how. Goodwill is not deductible for tax purposes.

The consolidated financial statements reflect consolidated revenue and net loss for AFV of $2,566 and $191, respectively, from October 11, 2011 to December 31, 2011. Had the Company acquired AFV on April 1, 2011, consolidated pro forma revenue and net loss for the nine months ended December 31, 2011 would have been $62,863 and $43,064, respectively, not including the financial results of Emer S.p.A. (“Emer”) (note 4(d)).

The Company incurred acquisition related expenses of $93 during the nine months ended December 31, 2011, which have been recorded in General and Administrative expenses in the consolidated statements of operations.

	(d)	Acquisition of Emer:

On July 1, 2011, the Company acquired, through its wholly owned subsidiary, Juniper Engines Italy S.r.l., 100% of the outstanding shares of Emer from the seller. The fair value of the consideration for the acquisition was $39,706. Westport paid cash of $17,607 on closing and issued 881,860 common shares with a value of $22,099 based on the NASDAQ closing price of the Company’s shares on July 1, 2011 of $25.06. The Company also assumed approximately $77,000 in existing net debt of Emer. Post-closing, Westport repaid approximately $36,300 of the debt, leaving approximately $40,700 in debt on the consolidated balance sheet as of July 1, 2011.

The acquisition was accounted for as a business combination using the acquisition method. The results of Emer have been included in the consolidated financial statements of the Company from July 1, 2011.

The Company obtained an independent third-party valuation of inventories, property and equipment, and intangible assets. The fair value of the assets acquired and liabilities assumed are as follows:

Consideration allocated to:
Property, plant and equipment		$	17,644
Other tangible assets, including cash of $11,073			60,532
Intangible assets subject to amortization over 5 to 20 years			32,954
Goodwill			50,774

Total assets acquired			161,904
Less:
Long-term debt			-83,272
Other liabilities			-38,926

Total net assets acquired		$	39,706

Consideration:
Cash		$	17,607
Common shares			22,099

		$	39,706

The foreign exchange rate used to translate Euro denominated net assets acquired, liabilities assumed and purchase consideration into U.S. dollars was 1.45 based on the July 1, 2011 closing rate.

The Company recognized goodwill associated with the transaction of $50,774. Goodwill includes the value of the assembled work force and expected synergies including access to markets and supply chain integration. Goodwill is not deductible for tax purposes.

The consolidated financial statements reflect consolidated revenue and net loss for Emer of $31,831 and $1,924, respectively, from July 1, 2011 to December 31, 2011. Had the Company acquired Emer on April 1, 2011, consolidated pro forma revenue and net loss for the nine-month period ended December 31, 2011 would have been $108,372 and $54,927, respectively, not including the financial results of AFV (note 4(c)).

The Company incurred acquisition related expenses of $1,683 during the nine months ended December 31, 2011, which have been recorded in General and Administrative expenses in the consolidated statements of operations.

Accounts_receivable

Accounts receivable	12 Months Ended
Accounts receivable	Dec. 31, 2013
Receivables [Abstract]	'
Loans, Notes, Trade and Other Receivables Disclosure [Text Block]	'
		5	Accounts receivable:

			December 31, 2013		December 31, 2012

	Customer trade receivable		$	54,017	$	39,754
	Government funding receivable			483		541
	Due from joint venture (note 21)			3,621		2,127
	Other receivables			2,689		1,916
	Income tax receivable			77		172
	Allowance for doubtful accounts			-1,572		-321

			$	59,315	$	44,189

Inventories

Inventories	12 Months Ended
Inventories	Dec. 31, 2013
Inventory Disclosure [Abstract]	'
Inventory Disclosure [Text Block]	'
		6	Inventories:

			December 31, 2013		December 31, 2012

	Purchased parts		$	25,616	$	25,454
	Assembled parts			881		4,870
	Work-in-process			9,889		7,516
	Finished goods			6,628		7,385
	Obsolescence provision			-2,388		-279

			$	40,626	$	44,946

	During the year ended December 31, 2013, the Company recorded a write-down to net realizable value of approximately $2,720 and an obsolescence charge of $2,205 (year ended December 31, 2012 - $233; nine months ended December 31, 2011 - $430). Cost of revenue related to product and parts revenue for the year ended December 31, 2013 was $148,690 (year ended December 31, 2013 - $102,486; nine months ended December 31, 2011 - $67,093).

Longterm_investments

Long-term investments	12 Months Ended
Long-term investments	Dec. 31, 2013
Long-term investments:	'
Cost and Equity Method Investments Disclosure [Text Block]	'
		7	Long-term investments:

			December 31, 2013			December 31, 2012

	Weichai Westport Inc. (a)		$	14,534		$	11,275
	Cummins Westport Inc. (b)			7,191			7,126
	Other equity accounted for investees			403			717

			$	22,128		$	19,118

	(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, 2013, the Company recognized its share of WWI’s income of $4,264 (year ended December 31, 2012 - $2,881; nine months ended December 31, 2011 - $1,438), 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, 2013			December 31, 2012

	Current assets:
	Cash and short-term investments		$	4,696		$	1,145
	Accounts receivable			31,967			21,512
	Inventory			80,412			55,109
	Other current assets			176			1,053
	Long-term assets
	Property, plant and equipment			7,021			4,930
	Deferred income tax assets			6,874			3,248

	Total assets		$	131,146		$	86,997

	Current liabilities:
	Accounts payable and accrued liabilities		$	71,345		$	49,125
	Other current liabilities			21,671			12,055

	Total liabilities		$	93,016		$	61,180

									Nine months ended
			Years ended December 31,						December 31,
			2013			2012			2011

	Product revenue		$	466,580		$	272,086		$	84,917

	Cost of revenue and expenses:
	Cost of product revenue			429,238			247,299			75,581
	Operating expenses			22,846			15,022			4,457
				452,084			262,321			80,038

	Income before income taxes			14,496			9,765			4,879

	Income tax expense			2,315			1,536			1,364

	Income for the period		$	12,181		$	8,229		$	3,515

	(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 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 previously contractually required to provide.

For the year ended December 31, 2013, the Company recognized its share of CWI’s income of $9,433 (year ended December 31, 2012 - $13,232; nine months ended December 31, 2011 - $12,958), as income from investment accounted for by the equity method.

Assets, liabilities, revenue and expenses of CWI are as follows:

		December 31, 2013			December 31, 2012

Current assets:
Cash and short-term investments		$	73,736		$	44,371
Accounts receivable			4,645			6,995
Current portion of deferred income tax assets			13,958			7,304
Other current assets			210			225
Long-term assets:
Property, plant and equipment			1,096			896
Deferred income tax assets			21,698			9,786

Total assets		$	115,343		$	69,577

Current liabilities:
Current portion of warranty liability		$	18,395		$	13,317
Current portion of deferred revenue			5,478			3,862
Accounts payable and accrued liabilities			7,772			9,401
			31,645			26,580

Long-term liabilities:
Warranty liability			49,174			17,501
Deferred revenue			17,815			9,968
Other long-term liabilities			2,400			1,312
			69,389			28,781

Total liabilities		$	101,034		$	55,361


								Nine months ended
		Years ended December 31,						December 31,
		2013			2012			2011

Product revenue		$	261,012		$	161,741		$	114,518
Parts revenue			49,639			36,274			24,326
			310,651			198,015			138,844

Cost of revenue and expenses:
Cost of product and parts revenue			246,403			136,575			78,837
Research and development			21,522			12,114			6,720
General and administrative			1,348			1,417			796
Sales and marketing			17,839			12,541			9,659
Foreign exchange (gain) loss			-7			-18			17
Bank charges, interest and other			607			472			369
			287,712			163,101			96,398

Income before undernoted			22,939			34,914			42,446

Interest and investment income			117			530			297

Income before income taxes			23,056			35,444			42,743

Income tax expense (recovery):
Current			24,600			16,362			18,602
Deferred			-18,566			-6,517			-1,775
			6,034			9,845			16,827

Income for the period		$	17,022		$	25,599		$	25,916

Variable_Interest_Entities

Variable Interest Entities

12 Months Ended

Dec. 31, 2013

Variable Interest Entities [Abstract]

Variable Interest Entities [Text Block]

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:

As at December 31, 2013

As at December 31, 2012

Carrying

Maximum

Carrying

Maximum

amount

exposure to

amount

exposure

loss

to loss

Equity method investment

7,191

7,126

Accounts receivable

3,621

2,127

Property_plant_and_equipment

Property, plant and equipment	12 Months Ended
Property, plant and equipment	Dec. 31, 2013
Property, Plant and Equipment [Abstract]	'
Property, Plant and Equipment Disclosure [Text Block]	'
		9	Property, plant and equipment:

					Accumulated		Net book
	December 31, 2013		Cost		depreciation		value

	Land and buildings		$	532	$	70	$	462
	Computer equipment and software			12,794		9,152		3,642
	Furniture and fixtures			6,414		2,408		4,006
	Machinery and equipment			96,656		42,439		54,217
	Leasehold improvements			16,422		11,400		5,022

			$	132,818	$	65,469	$	67,349

					Accumulated		Net book
	31-Dec-12		Cost		depreciation		value

	Land and buildings		$	575	$	64	$	511
	Computer equipment and software			11,529		8,140		3,389
	Furniture and fixtures			4,032		1,913		2,119
	Machinery and equipment			80,667		34,219		46,448
	Leasehold improvements			15,602		9,875		5,727

			$	112,405	$	54,211	$	58,194

	As at December 31, 2013, equipment with a cost of $18,788 (2012 - $16,532) and a net book value of $5,465 (2012 - $2,587) is held under capital lease.

	Depreciation expense for the year ended December 31, 2013 was $12,246 (year ended December 31, 2012 - $8,131; nine months ended December 31, 2011 - $4,394 ).

Intangible_assets

Intangible assets	12 Months Ended
Intangible assets	Dec. 31, 2013
Intangible Assets, Net (Excluding Goodwill) [Abstract]	'
Intangible Assets Disclosure [Text Block]	'
		10	Intangible assets:

					Accumulated		Net book
	31-Dec-13		Cost		amortization		value

	Patents and trademarks		$	20,974	$	2,900	$	18,074
	Technology			7,468		2,796		4,672
	Customer contracts			18,447		3,886		14,561
	Other intangibles			1,262		225		1,037

	Total		$	48,151	$	9,807	$	38,344

					Accumulated		Net book
	31-Dec-12		Cost		amortization		value

	Patents and trademarks		$	20,192	$	1,758	$	18,434
	Technology			6,961		1,901		5,060
	Customer contracts			14,404		2,709		11,695
	Other intangibles			44		18		26

	Total		$	41,601	$	6,386	$	35,215

	During the year ended December 31, 2013, amortization of $4,042 (December 31, 2012 - $3,264; nine months ended December 31, 2011 - $1,806) was recognized in the statement of operations.

	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 AFV 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.

	The expected amortization of intangible assets for fiscal 2014 to 2018 is $3,773 per year.

Goodwill

Goodwill	12 Months Ended
Goodwill	Dec. 31, 2013
Goodwill Disclosure [Abstract]	'
Goodwill Disclosure [Text Block]	'
		11	Goodwill:

	A continuity of goodwill is as follows:
			December 31, 2013		December 31, 2012

	Balance, beginning of period:		$	56,879	$	55,814
	Acquisition of BAF (note 4(a))			18,542		-
	Impairment losses			-34,964		-
	Impact of foreign exchange changes			1,043		1,065

	Balance, end of period		$	41,500	$	56,879

	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. 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.

	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.

Accounts_payable_and_accrued_l

Accounts payable and accrued liabilities	12 Months Ended
Accounts payable and accrued liabilities	Dec. 31, 2013
Accounts Payable and Accrued Liabilities, Current [Abstract]	'
Accounts Payable and Accrued Liabilities Disclosure [Text Block]	'
		12	Accounts payable and accrued liabilities:

			December 31, 2013		December 31, 2012

	Trade accounts payable		$	42,872	$	37,956
	Accrued payroll			7,937		8,539
	Accrued interest			893		961
	Income taxes payable			709		876
	Other payables			2,381		177

			$	54,792	$	48,509

Longterm_debt

Long-term debt	12 Months Ended
Long-term debt	Dec. 31, 2013
Debt Disclosure [Abstract]	'
Long-term Debt [Text Block]	'
		13	Long-term debt:

			December 31, 2013		December 31, 2012

	Subordinated debenture notes (a)		$	33,847	$	36,185
	Long-term payable (b)			-		9,836
	Senior financing (c)			15,941		18,812
	Senior revolving financing (c)			13,779		13,185
	Other bank financing (d)			403		1,171
	Capital lease obligations (e)			2,043		1,533
				66,013		80,722

	Current portion			-53,025		-28,566

			$	12,988	$	52,156

		(a)	On September 23, 2011, the Company raised $33,847 (CDN$36,000) through the issuance of debentures to Macquarie Private Wealth Inc. (“Macquarie”) on a private placement basis.

	The debentures are unsecured and subordinated to senior indebtedness, mature on September 22, 2014, 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, which commenced on March 15, 2012.

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

	The Company paid to Macquarie a cash commission equal to 3.85% of the gross proceeds of the offering totaling $1,460, which is included in other assets and amortized over the term of the debentures.

		(b)	On July 2, 2010, the Company acquired OMVL and a portion of the purchase price was payable on the third anniversary of the closing date. The amount was fully repaid on July 1, 2013.

		(c)	The senior financing agreement bears interest at the 6-month Euribor plus 2.5% or a rate of 2.8% as at December 31, 2013 and its carrying value is recorded at amortized cost using the effective interest rate method. The principal repayment schedule of the remaining senior financing is as follows for the years ended December 31:

	2014		$	4,274
	2015			4,662
	2016			4,856
	2017			2,428
	2018			-

			$	16,220

	The senior revolving financing facility bears interest at the 6-month Euribor plus 2.5% or a rate of 2.8% as at December 31, 2013 and will be repaid through two principal payments of $6,889 (€5,000) on March 31, 2016 and October 2, 2017.

	The Company has pledged its interest in Emer as a general guarantee for its senior financing and 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, 2013, the Company is in compliance with all covenants under the financing arrangements.

		(d)	Other bank financing consists of various unsecured bank financing arrangements that carry rates of interest ranging from 1.01% to 8.00% (2012 - 1.01% to 8.00%) and are payable on maturity dates ranging from June 23, 2014 to June 23, 2017.

		(e)	The Company has capital lease obligations that have initial terms of three to five years at interest rates ranging from 3.07% to 7.32% (2012 - 3.07% to 7.32%). The capital lease obligations require the following minimum annual payments during the respective fiscal years:

	2014		$	696
	2015			548
	2016			327
	2017			319
	2018			167
			$	2,057
	Amount representing interest			-14
			$	2,043

		(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% (2012 - 0.75%) per annum. As at December 31, 2013 and 2012, no amounts of this credit facility were drawn.

Warranty_liability

Warranty liability	12 Months Ended
Warranty liability	Dec. 31, 2013
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,					Nine months ended
			Years ended December 31,					December 31,
			2013		2012			2011

	Balance, beginning of period		$	6,380	$	4,401	$	1,314
	Warranty assumed on acquisition			582		-		-
	Warranty claims			-5,397		-3,099		-1,395
	Warranty accruals			4,153		5,303		4,530
	Change in estimate			22,837		-		-
	Impact of foreign exchange changes			290		-225		-48
	Balance, end of period		$	28,845	$	6,380	$	4,401

	Less: Current portion			-9,955		-2,072		-1,187

	Long-term portion		$	18,890	$	4,308	$	3,214

	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.

Other_longterm_liabilities

Other long-term liabilities	12 Months Ended
Other long-term liabilities	Dec. 31, 2013
Other Liabilities Disclosure [Abstract]	'
Other Liabilities Disclosure [Text Block]	'
		15	Other long-term liabilities:

			December 31,		December 31,
			2013		2012

	Severance indemnity (a)		$	1,547	$	1,681
	Contingent consideration payable related to AFV acquisition (b)			878		856
	Deferred lease inducements			16		69

			$	2,441	$	2,606

	(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 is estimated to have a fair value of $427 as at December 31, 2013 (December 31, 2012 - $442).

	The Company also records 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 is estimated to have a fair value of $451 as at December 31, 2013 (December 31, 2012 - $414).

Government_assistance

Government assistance	12 Months Ended
	Dec. 31, 2013
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, 2013 and 2012 and the nine months ended December 31, 2011, government assistance of $640, $842 and $604 was received or receivable by the Company, respectively, which has been recorded as a reduction of the related research and development expenditures (note 19).

	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 $1,269 (CDN$1,350) or 0.33% of the Company’s annual revenue provided that gross revenue exceeds $12,693 (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 $26,514 (CDN$28,200). For the year ended December 31, 2013, $1,350 (December 31, 2012 - $1,350) in royalties have been paid or are payable of which $1,269 (December 31, 2012 - $1,350) remains accrued in accounts payable and accrued liabilities as at December 31, 2013. As at December 31, 2013, cumulative royalties of CDN$6,750 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, 2013, 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

Share capital	12 Months Ended
	Dec. 31, 2013
Share capital:	'
Stockholders Equity Note Disclosure [Text Block]	'
		17	Share capital:

	During the year ended December 31, 2013, the Company issued 721,186 common shares, net of cancellations, upon exercises of stock options and share units (year ended December 31, 2012 – 513,490 common shares; nine months ended December 31, 2011 – 568,276 common shares). The Company issues shares from treasury to satisfy stock option and share unit exercises.

	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(a)).

	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.

	On October 11, 2011, the Company issued 33,161 common shares at a price of $28.74 per share as part of the consideration paid to acquire AFV (note 4(c)).

	On July 1, 2011, the Company issued 881,860 common shares at a price of $25.06 per share as part of the consideration paid to acquire Emer (note 4(d)).

Stock_options_and_other_stockb

Stock options and other stock-based plans	12 Months Ended
Stock options and other stock-based plans	Dec. 31, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
Disclosure of Compensation Related Costs, Share-based Payments [Text Block]	'
		18	Stock options and other stock-based plans:

	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, 2013, December 31, 2012 and December 31, 2011 and changes during the periods then ended are presented as follows:

				December 31, 2013					December 31, 2012					December 31, 2011
				Number of			Weighted		Number of shares			Weighted		Number of shares		Weighted
				shares			average					average				average
							exercise					exercise				exercise
							price					price				price
							(CDN $)					(CDN $)				(CDN $)

	Outstanding , beginning of period			996,047		$	27.78		328,027		$	8.96		562,014		$	8.46

	Granted			-			-		770,727			33.77		-			-
	Exercised			-111,986			6.8		-93,044			10.49		-225,845			7.87
	Forfeited/expired			-67,611			33.72		-9,663			33.36		-8,142			4.84

	Outstanding, end of period			816,450		$	30.2		996,047		$	27.78		328,027		$	8.96

	Options exercisable, end of period			305,506		$	24.15		226,487		$	8.06		311,360		$	8.55

	During the year ended December 31, 2013, the Company recognized $2,094 (year ended December 31, 2012 - $2,705; nine months ended December 31, 2011 - $352) in stock-based compensation related to stock options.

	No stock options were granted during the year ended December 31, 2013 or nine month period ended December 31, 2011.

	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, 2013, $2,409 of compensation cost related to stock option awards has yet to be recognized in results from operations and will be recognized over a weighted average period of 1.02 years.

	Range of exercise prices (CDN $)						Number		Weighted		Weighted			Number			Weighted
							outstanding,		average		average			exercisable,			average
							December 31,		remaining		exercise			December 31,			exercise
							2013		contractual		price			2013			price
									life		(CDN$)						(CDN $)
	$	3.22	to	$	3.47		5,504		0.5		$	3.29		5,504		$	3.29
		4.24	to		4.27		21,900		0.7			4.27		21,900			4.27
		9.1	to		11.11		79,237		1			10.79		79,237			10.79
		14.9	to		16.5		16,903		1.9			15.69		16,903			15.69
		29.76	to		33.83		692,906		3			33.8		181,962			33.78

	$	3.22	to	$	33.83		816,450		2.7		$	30.2		305,506		$	24.15

		(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, 2013, the Company recognized $12,189 (year ended December 31, 2012 - $9,763; nine months ended December 31, 2011 – $5,827) 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, 2013, December 31, 2012 and December 31, 2011 are as follows:

			December 31, 2013					December 31, 2012					December 31, 2011
			Number of		Weighted			Number of		Weighted			Number of		Weighted
			units		average			units		average			units		average
					grant					grant					grant
					date fair					date fair					date fair
			value			value				value
			(CDN $)			(CDN $)				(CDN $)

Outstanding, beginning of period		1,095,094			$	20.68			1,250,917		$	18.04		1,377,237		$	12.19
Granted		742,140		$	30.21		185,705		$	35.99		269,292		$	35.7
Exercised/Vested		-448,526		$	24.44		-337,228		$	19.34		-391,612		$	9.61
Forfeited/expired		-188,117		$	29.8		-4,300		$	19.67		-4,000		$	18.61

Outstanding, end of period		1,200,591		$	23.68		1,095,094		$	20.68		1,250,917		$	18.04

Units outstanding and exercisable, end of period		224,638		$	11.2		262,615		$	8.86		276,931		$	7.97

		Year ended December 31,					Year ended December					Nine months ended
		2013					31, 2012					December 31, 2011
		Number of		Weighted			Number of		Weighted			Number of		Weighted
		units		average			units		average			units		average
				grant					grant					grant
				date fair					date fair					date fair
				value					value					value
				(CDN $)					(CDN $)					(CDN $)

Unvested, beginning of period		832,479		$	24.41		973,986		$	20.9		835,703		$	15.62
Granted		742,140		$	30.16		185,705		$	35.99		269,292		$	35.7
Vested		-410,549		$	27.34		-322,912		$	21.64		-127,009		$	17.55
Forfeited		-188,117		$	29.8		-4,300		$	18.61		-4,000		$	18.61

Unvested, end of period		975,953		$	26.55		832,479		$	24.41		973,986		$	20.9

As at December 31, 2013, $16,590 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 1.86 years.

Of the Units granted during the year ended December 31, 2013, 389,685 Units (December 31, 2012 – 66,428) were subject to market and service conditions. The fair value of these Units was determined using a Monte-Carlo simulation using the following weighted average assumptions: expected dividend yield - nil%; expected stock price volatility – 56.16%; and risk free interest rate – 1.17%. The valuation model determined the grant date fair value based on assumptions about the likelihood of the Company achieving different payout factors as driven by the market conditions. The weighted average grant date fair value was $30.72 for Units granted for the year ended December 31, 2013 (December 31, 2012 - $35.99). For the Units granted after January 1, 2013, Units are based on two-year revenue growth, with a three-year total shareholder return (“TSR”) gate that caps payouts as 100% unless Westport TSR relative to the Ardour Global Alternative Energy Index North America (“AGINA”) equals or exceeds median. Payouts may occur at 0% to 200% of the level awarded based on the fulfillment of the applicable performance. 100% of these Units vest after three years from the date of the grant. For the Units granted during the year ended December 31, 2012, payout factors are determined based upon the absolute stock price at the end of two years, equal to the closing price on the last trading day of December 31, 2013. One-half of these Units vest after two years and the remainder after three years from the date of the grant. The impact of market conditions, if any, on compensation expense for these units is determined at the time of the grant with no adjustment to the compensation expense for the actual results of the market condition. The fair value of all other Units was determined based on the market price of the underlying shares on the date of grant. For the Units granted prior to January 1, 2012, payout factors are determined based upon the absolute stock price at the end of two years and the stock price relative to a Synthetic Clean Tech index of comparative companies two years after the grant date. One-half of these Units vest after two years and the remainder after three years from the date of the grant. The impact of market conditions, if any, on compensation expense for these units is determined at the time of the grant with no adjustment to the compensation expense for the actual results of the market condition. During the year ended December 31, 2013, 160,674 PSUs (2012 – 83,218) vested with a payout factor of 200% (2012 – 200%) and 54,876 PSUs vested with a payout factor of 0% and were forfeited.

	(c)	Aggregate intrinsic values:

The aggregate intrinsic value of the Company’s stock option awards and share units at December 31, 2013 and 2012 are as follows:

		December 31,				December 31,
		2013				2012
		CDN$				CDN$

Stock options:
Outstanding		$	1,337			$	4,219
Exercisable			1,337				4,137
Exercised			2,667				2,398

Share units:
Outstanding		$	24,960			$	28,823
Exercisable			4,670				6,912
Exercised			18,041				15,135

	(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,						Nine months ended
		2013			2012			December 31, 2011

Research and development		$	2,195		$	2,251		$	825
General and administrative			10,201			6,752			3,302
Sales and marketing			1,887			3,465			2,052

		$	14,283		$	12,468		$	6,179

Research_and_development_expen

Research and development expenses	12 Months Ended
Research and development expenses	Dec. 31, 2013
Research and Development [Abstract]	'
Research, Development, and Computer Software Disclosure [Text Block]	'
		19	Research and development expenses:

	Research and development expenses are recorded net of program funding received or receivable. The research and development expenses had been incurred and program funding had been received or are receivable as follows:

							Nine months ended
		Years ended December 31,					December 31,
			2013	2012			2011
	Research and development expenses	$	91,772	$	74,040	$	37,178
	Program funding (note 16)		-640		-842		-604

	Research and development	$	91,132	$	73,198	$	36,574

Income_taxes

Income taxes	12 Months Ended
Income taxes	Dec. 31, 2013
Income Tax Disclosure [Abstract]	'
Income Tax Disclosure [Text Block]	'
		20	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, 2013 (year ended December 31, 2012 – 25%; nine months ended December 31, 2011 – 26.5%) as follows:

						Nine months ended
			Years ended December 31,			December 31,
			2013		2012	2011

	Loss before income taxes	$	-184,537	$	-97,036	$	-46,954

	Expected income tax recovery		-47,979		-24,259		-12,443

	Increase (reduction) in income taxes resulting from:
	Non-deductible stock-based compensation		3,619		3,019		1,642
	Other permanent differences		-2,562		-2,158		87
	Withholding taxes		590		1,187		500
	Change in enacted rates		-		62		189
	Foreign tax rate differences, foreign exchange and other adjustments		3,858		-382		-552
	Non-taxable income from equity investment		-2,851		-3,308		-3,974
	Change in valuation allowance		37,391		27,577		13,391
	Goodwill impairment		8,807		-		-

	Income tax expense (recovery)	$	873	$	1,738	$	-1,160

		(b)	The significant components of the deferred income tax assets and liabilities are as follows:

		December 31, 2013		December 31, 2012
	Deferred income tax assets:
	Net loss carry forwards	$	108,083	$	76,496
	Intangible assets		4,276		1,557
	Property, plant and equipment		5,446		5,703
	Financing and share issuance costs		2,696		3,248
	Warranty liability		5,726		2,013
	Deferred revenue		1,191		1,601
	Inventory		2,017		2,300
	Unrealized foreign exchange		21		595
	Research and development		2,341		2,132
	Other		6,410		3,917

	Total gross deferred income tax assets		138,207		99,562
	Valuation allowance		-126,424		-89,033

	Total deferred income tax assets		11,783		10,529

	Deferred income tax liabilities:
	Intangible assets		9,884		8,784
	Property, plant and equipment		3,132		3,297
	Other		650		575
	Total deferred income tax liabilities		13,666		12,656

	Total net deferred income tax liabilities	$	1,883	$	2,127

	Allocated as follows:
	Current deferred income tax assets		3,109		7,183
	Current deferred income tax liabilities		-468		-65
	Long-term deferred income tax assets		379		-
	Long-term deferred income tax liabilities		-4,903		-9,245
	Total net deferred income tax liabilities	$	-1,883	$	-2,127

	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 income during the future periods in which those temporary differences are expected to reverse. If the evidence does not exist that all the deferred income tax assets will be fully realized, a valuation allowance has been recorded.

	The following is a summary of the changes in the deferred income tax asset valuation allowance:

		Year ended		Year ended
		December 31, 2013			December 31, 2012

Beginning balance		$	89,033	$	61,456
Additions			37,391		27,639
Reductions			-		-62

Ending valuation allowance		$	126,424	$	89,033

	(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, 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

Nine months ended December 31, 2011:
Canada		$	-45,899	$	500	$	-	$	500
United States			-1,862		95		-		95
Italy			-1,342		388		-2,205		-1,817
Other			2,149		45		17		62

		$	-46,954	$	1,028	$	-2,188	$	-1,160

(d) As at December 31, 2013, there were no uncertain tax positions that require recognition in the consolidated financial statements. 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 2013 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.

	(e)	The Company has loss carry forwards in the various jurisdictions available to offset future taxable income as follows:

Expiring in:		2014		2015		2016		2017		2018			2026 and later	Total

Canada		$	2,018	$	2,358	$	-	$	-	$	-	$	341,701	$	346,077
Italy			-		-		-		-		-		4,585		4,585
United States			-		-		-		-		-		31,573		31,573
Sweden			-		-		-		-		-		9,678		9,678
Other			-		-		-		1,018		7,017		3,204		11,239

Total		$	2,018	$	2,358	$	-	$	1,018	$	7,017	$	390,741	$	403,152

Related_party_transactions

Related party transactions	12 Months Ended
Related party transactions	Dec. 31, 2013
Related Party Transactions [Abstract]	'
Related Party Transactions Disclosure [Text Block]	'
	21.	Related party transactions:

	Pursuant to the amended and restated JVA, Westport engages in transactions with CWI.

	As at December 31, 2013, net amounts due from CWI total $3,621 (2012 - $2,127). 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:

								Nine months ended
			Years ended December 31,					December 31,
			2013		2012			2011

	Research and development		$	178	$	160	$	148
	General and administrative			1,351		2,621		338
	Sales and marketing			4,725		3,683		2,598

			$	6,254	$	6,464	$	3,084

	During the year ended December 31, 2013, interest of $nil (year ended December 31, 2012 - $114; nine months ended December 31, 2011 - $116) was paid to CWI.

	All material transactions between the Company and CWI have been eliminated on application of equity accounting.

Service_and_other_revenue

Service and other revenue	12 Months Ended
	Dec. 31, 2013
Service And Other Revenue [Abstract]	'
Service And Other Revenue Disclosure [Text Block]	'
		22	Service and other revenue:

	Service and other revenue for the year ended December 31, 2013 consisted of a one-time license revenue of $nil (year ended December 31, 2012 - $ 7,923; nine months ended December 31, 2011 - $nil) for the transfer of proprietary know-how, other fee payments of $1,484 (year ended December 31, 2012 - $1,414; nine months ended December 31, 2011 - $nil), and service revenue of $14,547 (year ended December 31, 2012 - $13,907; nine months ended December 31, 2011 - $10,181) under existing development agreements was recognized as the Company achieved and delivered certain milestones. 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
Commitments and contingencies	Dec. 31, 2013
Commitments and Contingencies Disclosure [Abstract]	'
Commitments and Contingencies Disclosure [Text Block]	'
		23	Commitments and contingencies:

	The Company has obligations under operating lease arrangements that require the following minimum annual payments during the respective fiscal years:

	2014		$	4,613
	2015			4,339
	2016			6,331
	2017			6,471
	2018			5,080
	Thereafter			57,322

			$	84,156

	For the year ended December 31, 2013, the Company incurred operating lease expense of $5,675 (year ended December 31, 2012 - $4,492; nine months ended December 31, 2011 - $2,070).

	As at December 31, 2013, the Company’s wholly owned subsidiary Emer has provided a total amount of guarantees to third parties of $342 (€248), 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.

Segmented_information

Segmented information	12 Months Ended
Segmented information	Dec. 31, 2013
Segment Reporting [Abstract]	'
Segment Reporting Disclosure [Text Block]	'
	24.	Segmented information:

	In December 2012, the Company realigned its business units to focus on product commercialization and global partnerships development. To accommodate the variety in product, system and service solutions, Westport created three new reportable operating segments. 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 is 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^TM high pressure direct injection (HPDI) technology, Westport^TM 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, 2013 and December 31, 2012.

										Nine months ended
			Years ended December 31,							December 31,
			2013			2012				2011

	Revenue:
	Applied Technologies		$	93,216		$	91,675		$	55,064
	On-Road Systems			55,090			37,558			20,816
	Off-Road Systems			3,309			3,149			1,635
	Corporate and Technology Investments			12,417			23,244			10,181
	CWI			310,651			198,015			138,844
	WWI			466,580			272,086			84,917
	Total segment revenues			941,263			625,727			311,457
	Less: equity investees' revenue			-777,231			-470,101			-223,761
	Total consolidated revenues		$	164,032		$	155,626		$	87,696

	Net consolidated operating income (loss) excluding depreciation and amortization, losses on impairments, write-downs and disposals, foreign exchange loss (gain), bank charges and other:
	Applied Technologies		$	6,635		$	9,820		$	974
	On-Road Systems			-59,843			-40,937			-27,431
	Off-Road Systems			-14,218			-13,653			-4,401
	Corporate and Technology Investments			-83,546			-50,211			-23,153
	CWI			23,539			35,368			42,832
	WWI			14,496			9,765			4,879
	Total segment operating loss			-112,937			-49,848			-6,300
	Less: equity investees’ operating income			-38,035			-45,133			-47,711
	Net consolidated operating loss excluding depreciation and amortization, losses on impairments, write-downs and disposals, foreign exchange (gain) loss, bank charges and other:			-150,972			-94,981			-54,011

	Depreciation and amortization:
	Applied Technologies			7,838			7,905			5,013
	On-Road Systems			3,186			1,028			94
	Off-Road Systems			450			83			-
	Corporate and Technology Investments			4,814			2,379			1,093

	Losses on impairments, write-downs and disposals
	Applied Technologies			31,564			-			-
	On-Road Systems			9,959			-			-
				57,811			11,395			6,200

	Net consolidated operating loss before foreign exchange (gain) loss, bank charges and other			-208,783			-106,376			-60,211

	Foreign exchange (gain) loss, bank charges and other			-14,573			1,922			-1,136

Loss before undernoted			-194,210			-108,298			-59,075

Interest on long-term debt and other income (expenses), net			-3,771			-4,928			-2,337
Income from investment accounted for by the equity method			13,444			16,190			14,458

Loss before income taxes		$	-184,537		$	-97,036		$	-46,954

									Nine months ended
		Years ended December 31,							December 31,
		2013			2012				2011

Total additions to long-lived assets excluding business combinations:
Applied Technologies		$	4,408		$	3,000		$	2,201
On-Road Systems			15,555			10,306			645
Off-Road Systems			908			1,481			-
Corporate and Technology Investments			5,579			16,565			10,400

		$	26,450		$	31,352		$	13,246

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
								Nine months ended
		Years ended December 31,						December 31,
		2013			2012			2011

Americas (including United States)		42				38		28
Asia (including China)		11				9		15
Other (including Italy)		47				53		57

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, 2013, total goodwill of $22,958 (December 31, 2012 - $51,711) was allocated to Applied Technologies and $18,542 (December 31, 2012 - $5,168) On-Road Systems segments.

As at December 31, 2013, total long-term investments of $21,872 (December 31, 2012 - $18,544) was allocated to the Corporate segment and $256 (December 31, 2012 - $574) was allocated to the On-Road Systems. Total assets are allocated as follows:

		December 31, 2013			December 31, 2012

Applied Technologies		$	144,803		$	161,206
On-Road Systems			111,323			85,401
Off-Road Systems			6,564			6,556
Corporate and Technology Investments and unallocated assets			228,981			236,914
CWI			115,343			69,577
WWI			131,146			86,997
			738,160			646,651
Less: equity investees’ total assets			246,489			156,574

Total consolidated assets		$	491,671		$	490,077

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, 2013			December 31, 2012

Italy		$	66,918		$	99,099
Canada			30,713			29,707
United States			47,322			12,463
Sweden			322			7,720
China			8,675			6,524
Australia			1,360			601
		$	155,310		$	156,114
Less: equity investees’ long-lived assets			8,117			5,826

Total consolidated long-lived assets		$	147,193		$	150,288

Financial_instruments

Financial instruments	12 Months Ended
Financial instruments	Dec. 31, 2013
Financial Instruments Disclosure [Abstract]	'
Financial Instruments Disclosure [Text Block]	'
		25	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, 2013, the Company has $210,604 of cash, cash equivalents and short-term investments.

	The following are the contractual maturities of financial obligations as at December 31, 2013:

			Carrying		Contractual		< 1 year		1-3 years		4-5 years		>5 years
			amount		cash flows		< 1 year		1-3 years		4-5 years		>5 years

	Accounts payable and accrued liabilities		$	53,523	$	53,523	$	53,523	$	-	$	-	$	-
	Unsecured subordinated debentures ⁽¹⁾			33,847		36,902		36,902		-		-		-
	Senior financing ⁽²⁾			15,941		17,167		4,705		9,999		2,463		-
	Senior revolving financing ⁽³⁾			13,779		14,171		14,171		-		-		-
	Other bank financing			403		403		403		-		-		-
	Other long-term debt			2,043		2,057		696		875		486		-
	Operating lease commitments			-		84,154		4,613		10,670		11,549		57,322
	Royalty payments ⁽⁴⁾			1,269		20,149		1,269		2,538		2,529		13,813

			$	120,805	$	228,526	$	116,332	$	24,082	$	17,027	$	71,135

	(1)Includes interest at 9%.
	(2)Includes interest at 2.8% the rate in effect at December 31, 2013
	(3)Includes interest at 2.8%, the rate in effect at December 31, 2013
	(4)From fiscal 2011 to 2015 inclusive, the Company is obligated to pay annual royalties equal to the greater of $1,269 (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.

	The Company expects to be able to meet its future financial obligations with its current source of funds. However, there are uncertainties related to the timing of the Company’s cash inflows and outflows, specifically around the sale of inventories and amounts required for market and product development costs. These uncertainties include the volume of commercial sales related to its natural gas engines and fuel system products and the development of markets for, and customer acceptance of, these products. As a result, the Company may need to seek additional equity or arrange debt financing, which could include additional lines of credit, in order to meet its financial obligations.

		(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, 2013, 88% (December 31, 2012 - 89%) of accounts receivable relates to customer receivables, 1% (December 31, 2012 - 1%) relates to government grants receivable and 11% (December 31, 2012 - 10%) 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, 2013 of $269,919 (December 31, 2012 - $260,049) 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, 2013 is as follows:

			U.S. dollars
	Cash and cash equivalents		$	150,595
	Short-term investments			31,820
	Accounts receivable			16,607
	Accounts payable			8,732

			Euros
	Cash and cash equivalents		€	387

	If foreign exchange rates on December 31, 2013 had changed by 25 basis points, with all other variables held constant, net loss for the year ended December 31, 2013 would have changed by $528 and $1 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, 2013 had increased or decreased by 50 basis points, with all other variables held constant, net loss for the year ended December 31, 2013 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 12(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(c)) approximates its fair value as at December 31, 2013, as the interest rate on the debt is floating and therefore approximates the market rate of interest. The Company’s credit spread also has not substantially changed from the 2.5% premium 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, 2013, cash and cash equivalents and short-term investments are measured at fair value on a recurring basis and are included in Level 1.

Significant_accounting_policie1

Significant accounting policies (Policies)

12 Months Ended

Dec. 31, 2013

Accounting Policies [Abstract]

Basis of Accounting, Policy [Policy Text Block]

(a)

Basis of presentation:

These consolidated financial statements are presented in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”).

Foreign Currency Transactions and Translations Policy [Policy Text Block]

(b)

Foreign currency translation:

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, 2013

December 31, 2012

December 31, 2013

December 31, 2012

Canadian dollar

0.94

1.01

0.97

Australian dollar

0.89

1.04

0.97

1.04

Euro

1.38

1.32

1.33

1.29

RMB

0.17

0.16

Swedish Krona

0.16

0.15

Cash and Cash Equivalents, Policy [Policy Text Block]

(c)

Cash and cash equivalents:

Short Term Investments [Policy Text Block]

(d)

Short-term investments:

Receivables, Policy [Policy Text Block]

(e)

Accounts receivable:

Inventory, Policy [Policy Text Block]

(f)

Inventories:

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

10 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:

Financial Liabilities [Policy Text Block]

(i)

Financial liabilities:

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:

Goodwill and Intangible Assets, Intangible Assets, Policy [Policy Text Block]

(l)

Intangible assets:

Asset Retirement Obligations, Policy [Policy Text Block]

(m)

Impairment of long-lived assets:

Goodwill and Intangible Assets, Policy [Policy Text Block]

(n)

Goodwill impairment:

Standard Product Warranty, Policy [Policy Text Block]

(o)

Warranty liability:

Extended Product Warranty, Policy [Policy Text Block]

(p)

Extended warranty:

Revenue Recognition, Policy [Policy Text Block]

(q)

Revenue recognition:

Product revenue

Revenue from research and development

Revenue from contracts

License revenue

Income Tax, Policy [Policy Text Block]

(r)

Income taxes:

Significant_accounting_policie2

Significant accounting policies (Tables)

12 Months Ended

Dec. 31, 2013

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, 2013

December 31, 2012

December 31, 2013

December 31, 2012

Canadian dollar

0.94

1.01

0.97

Australian dollar

0.89

1.04

0.97

1.04

Euro

1.38

1.32

1.33

1.29

RMB

0.17

0.16

Swedish Krona

0.16

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

10 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
Business combinations (Tables)	Dec. 31, 2013
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.

		Assigned fair value		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

Schedule of Finite-Lived Intangible Assets Acquired as Part of Business Combination [Table Text Block]	'
	The fair value of the assets acquired and liabilities assumed are as follows:

	Consideration allocated to:
	Total tangible assets	$	685
	Intangible assets subject to amortization over 8 years		832

	Total assets acquired		1,517
	Less: total liabilities		-392

	Total net assets acquired	$	1,125

AFV [Member]	'
Schedule Of Purchase Price Allocations [Table Text Block]	'
	The fair value of the assets acquired and liabilities assumed are as follows:

	Consideration allocated to:
	Total tangible assets, including cash of $8	$	2,161
	Intangible assets subject to amortization over 8 years		2,638
	Goodwill		2,701

	Total assets acquired		7,500
	Less: total liabilities		-3,561

	Total net assets acquired	$	3,939

	Consideration:
	Cash	$	2,558
	Common shares		953
	Contingent consideration payable		428

		$	3,939

Emer [Member]	'
Schedule Of Purchase Price Allocations [Table Text Block]	'
	The Company obtained an independent third-party valuation of inventories, property and equipment, and intangible assets. The fair value of the assets acquired and liabilities assumed are as follows:

	Consideration allocated to:
	Property, plant and equipment	$	17,644
	Other tangible assets, including cash of $11,073		60,532
	Intangible assets subject to amortization over 5 to 20 years		32,954
	Goodwill		50,774

	Total assets acquired		161,904
	Less:
	Long-term debt		-83,272
	Other liabilities		-38,926

	Total net assets acquired	$	39,706

	Consideration:
	Cash	$	17,607
	Common shares		22,099

		$	39,706

Accounts_receivable_Tables

Accounts receivable (Tables)	12 Months Ended
Accounts receivable (Tables)	Dec. 31, 2013
Receivables [Abstract]	'
Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block]	'
		December 31, 2013		December 31, 2012

	Customer trade receivable	$	54,017	$	39,754
	Government funding receivable		483		541
	Due from joint venture (note 21)		3,621		2,127
	Other receivables		2,689		1,916
	Income tax receivable		77		172
	Allowance for doubtful accounts		-1,572		-321

		$	59,315	$	44,189

Inventories_Tables

Inventories (Tables)	12 Months Ended
Inventories (Tables)	Dec. 31, 2013
Inventory Disclosure [Abstract]	'
Schedule of Inventory, Current [Table Text Block]	'
		December 31, 2013		December 31, 2012

	Purchased parts	$	25,616	$	25,454
	Assembled parts		881		4,870
	Work-in-process		9,889		7,516
	Finished goods		6,628		7,385
	Obsolescence provision		-2,388		-279

		$	40,626	$	44,946

Longterm_investments_Tables

Long-term investments (Tables)	12 Months Ended
Long-term investments (Tables)	Dec. 31, 2013
Long Term Investment [Table Text Block]	'
		December 31, 2013		December 31, 2012

	Weichai Westport Inc. (a)	$	14,534	$	11,275
	Cummins Westport Inc. (b)		7,191		7,126
	Other equity accounted for investees		403		717

		$	22,128	$	19,118

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, 2013		December 31, 2012

	Current assets:
	Cash and short-term investments	$	4,696	$	1,145
	Accounts receivable		31,967		21,512
	Inventory		80,412		55,109
	Other current assets		176		1,053
	Long-term assets
	Property, plant and equipment		7,021		4,930
	Deferred income tax assets		6,874		3,248

	Total assets	$	131,146	$	86,997

	Current liabilities:
	Accounts payable and accrued liabilities	$	71,345	$	49,125
	Other current liabilities		21,671		12,055

	Total liabilities	$	93,016	$	61,180

						Nine months ended
		Years ended December 31,				December 31,
		2013		2012		2011

	Product revenue	$	466,580	$	272,086	$	84,917

	Cost of revenue and expenses:
	Cost of product revenue		429,238		247,299		75,581
	Operating expenses		22,846		15,022		4,457
			452,084		262,321		80,038

	Income before income taxes		14,496		9,765		4,879

	Income tax expense		2,315		1,536		1,364

	Income for the period	$	12,181	$	8,229	$	3,515

Cummins Westport, Inc. [Member]	'
Schedule of Equity Method Investments [Table Text Block]	'
	Assets, liabilities, revenue and expenses of CWI are as follows:

		December 31, 2013		December 31, 2012

	Current assets:
	Cash and short-term investments	$	73,736	$	44,371
	Accounts receivable		4,645		6,995
	Current portion of deferred income tax assets		13,958		7,304
	Other current assets		210		225
	Long-term assets:
	Property, plant and equipment		1,096		896
	Deferred income tax assets		21,698		9,786

	Total assets	$	115,343	$	69,577

	Current liabilities:
	Current portion of warranty liability	$	18,395	$	13,317
	Current portion of deferred revenue		5,478		3,862
	Accounts payable and accrued liabilities		7,772		9,401
			31,645		26,580

	Long-term liabilities:
	Warranty liability		49,174		17,501
	Deferred revenue		17,815		9,968
	Other long-term liabilities		2,400		1,312
			69,389		28,781

	Total liabilities	$	101,034	$	55,361

						Nine months ended
		Years ended December 31,				December 31,
		2013		2012		2011

	Product revenue	$	261,012	$	161,741	$	114,518
	Parts revenue		49,639		36,274		24,326
			310,651		198,015		138,844

	Cost of revenue and expenses:
	Cost of product and parts revenue		246,403		136,575		78,837
	Research and development		21,522		12,114		6,720
	General and administrative		1,348		1,417		796
	Sales and marketing		17,839		12,541		9,659
	Foreign exchange (gain) loss		-7		-18		17
	Bank charges, interest and other		607		472		369
			287,712		163,101		96,398

	Income before undernoted		22,939		34,914		42,446

	Interest and investment income		117		530		297

	Income before income taxes		23,056		35,444		42,743

	Income tax expense (recovery):
	Current		24,600		16,362		18,602
	Deferred		-18,566		-6,517		-1,775
			6,034		9,845		16,827

	Income for the period	$	17,022	$	25,599	$	25,916

Variable_Interest_Entities_Tab

Variable Interest Entities (Tables)

12 Months Ended

Dec. 31, 2013

Variable Interest Entities [Abstract]

Schedule of Variable Interest Entities [Table Text Block]

As at December 31, 2013

As at December 31, 2012

Carrying

Maximum

Carrying

Maximum

amount

exposure to

amount

exposure

loss

to loss

Equity method investment

7,191

7,126

Accounts receivable

3,621

2,127

Property_plant_and_equipment_T

Property, plant and equipment (Tables)	12 Months Ended
Property, plant and equipment (Tables)	Dec. 31, 2013
Property, Plant and Equipment [Abstract]	'
Property, Plant and Equipment [Table Text Block]	'
				Accumulated		Net book
	December 31, 2013	Cost		depreciation		value

	Land and buildings	$	532	$	70	$	462
	Computer equipment and software		12,794		9,152		3,642
	Furniture and fixtures		6,414		2,408		4,006
	Machinery and equipment		96,656		42,439		54,217
	Leasehold improvements		16,422		11,400		5,022

		$	132,818	$	65,469	$	67,349

				Accumulated		Net book
	31-Dec-12	Cost		depreciation		value

	Land and buildings	$	575	$	64	$	511
	Computer equipment and software		11,529		8,140		3,389
	Furniture and fixtures		4,032		1,913		2,119
	Machinery and equipment		80,667		34,219		46,448
	Leasehold improvements		15,602		9,875		5,727

		$	112,405	$	54,211	$	58,194

Intangible_assets_Tables

Intangible assets (Tables)	12 Months Ended
Intangible assets (Tables)	Dec. 31, 2013
Intangible Assets, Net (Excluding Goodwill) [Abstract]	'
Schedule of Finite-Lived Intangible Assets [Table Text Block]	'
				Accumulated		Net book
	31-Dec-13	Cost		amortization		value

	Patents and trademarks	$	20,974	$	2,900	$	18,074
	Technology		7,468		2,796		4,672
	Customer contracts		18,447		3,886		14,561
	Other intangibles		1,262		225		1,037

	Total	$	48,151	$	9,807	$	38,344

				Accumulated		Net book
	31-Dec-12	Cost		amortization		value

	Patents and trademarks	$	20,192	$	1,758	$	18,434
	Technology		6,961		1,901		5,060
	Customer contracts		14,404		2,709		11,695
	Other intangibles		44		18		26

	Total	$	41,601	$	6,386	$	35,215

Goodwill_Tables

Goodwill (Tables)	12 Months Ended
Goodwill (Tables)	Dec. 31, 2013
Goodwill Disclosure [Abstract]	'
Schedule of Goodwill [Table Text Block]	'
	A continuity of goodwill is as follows:
		December 31, 2013		December 31, 2012

	Balance, beginning of period:	$	56,879	$	55,814
	Acquisition of BAF (note 4(a))		18,542		-
	Impairment losses		-34,964		-
	Impact of foreign exchange changes		1,043		1,065

	Balance, end of period	$	41,500	$	56,879

Accounts_payable_and_accrued_l1

Accounts payable and accrued liabilities (Tables)	12 Months Ended
Accounts payable and accrued liabilities (Tables)	Dec. 31, 2013
Accounts Payable and Accrued Liabilities, Current [Abstract]	'
Schedule of Accounts Payable and Accrued Liabilities [Table Text Block]	'
		December 31, 2013		December 31, 2012

	Trade accounts payable	$	42,872	$	37,956
	Accrued payroll		7,937		8,539
	Accrued interest		893		961
	Income taxes payable		709		876
	Other payables		2,381		177

		$	54,792	$	48,509

Longterm_debt_Tables

Long-term debt (Tables)	12 Months Ended
Long-term debt (Tables)	Dec. 31, 2013
Debt Disclosure [Abstract]	'
Schedule of Long-term Debt Instruments [Table Text Block]	'
			December 31, 2013		December 31, 2012

	Subordinated debenture notes (a)		$	33,847	$	36,185
	Long-term payable (b)			-		9,836
	Senior financing (c)			15,941		18,812
	Senior revolving financing (c)			13,779		13,185
	Other bank financing (d)			403		1,171
	Capital lease obligations (e)			2,043		1,533
				66,013		80,722

	Current portion			-53,025		-28,566

			$	12,988	$	52,156

		(a)	On September 23, 2011, the Company raised $33,847 (CDN$36,000) through the issuance of debentures to Macquarie Private Wealth Inc. (“Macquarie”) on a private placement basis.

	The debentures are unsecured and subordinated to senior indebtedness, mature on September 22, 2014, 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, which commenced on March 15, 2012.

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

	The Company paid to Macquarie a cash commission equal to 3.85% of the gross proceeds of the offering totaling $1,460, which is included in other assets and amortized over the term of the debentures.

		(b)	On July 2, 2010, the Company acquired OMVL and a portion of the purchase price was payable on the third anniversary of the closing date. The amount was fully repaid on July 1, 2013.

		(c)	The senior financing agreement bears interest at the 6-month Euribor plus 2.5% or a rate of 2.8% as at December 31, 2013 and its carrying value is recorded at amortized cost using the effective interest rate method. The principal repayment schedule of the remaining senior financing is as follows for the years ended December 31:

	2014		$	4,274
	2015			4,662
	2016			4,856
	2017			2,428
	2018			-

			$	16,220

	The senior revolving financing facility bears interest at the 6-month Euribor plus 2.5% or a rate of 2.8% as at December 31, 2013 and will be repaid through two principal payments of $6,889 (€5,000) on March 31, 2016 and October 2, 2017.

	The Company has pledged its interest in Emer as a general guarantee for its senior financing and 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, 2013, the Company is in compliance with all covenants under the financing arrangements.

		(d)	Other bank financing consists of various unsecured bank financing arrangements that carry rates of interest ranging from 1.01% to 8.00% (2012 - 1.01% to 8.00%) and are payable on maturity dates ranging from June 23, 2014 to June 23, 2017.

		(e)	The Company has capital lease obligations that have initial terms of three to five years at interest rates ranging from 3.07% to 7.32% (2012 - 3.07% to 7.32%). The capital lease obligations require the following minimum annual payments during the respective fiscal years:

	2014		$	696
	2015			548
	2016			327
	2017			319
	2018			167
			$	2,057
	Amount representing interest			-14
			$	2,043

Schedule of Maturities of Long-term Debt [Table Text Block]	'
	The principal repayment schedule of the remaining senior financing is as follows for the years ended December 31:

	2014		$	4,274
	2015			4,662
	2016			4,856
	2017			2,428
	2018			-

			$	16,220

Schedule of Future Minimum Lease Payments for Capital Leases [Table Text Block]	'
	The capital lease obligations require the following minimum annual payments during the respective fiscal years:

	2014		$	696
	2015			548
	2016			327
	2017			319
	2018			167
			$	2,057
	Amount representing interest			-14
			$	2,043

Warranty_liability_Tables

Warranty liability (Tables)	12 Months Ended
Warranty liability (Tables)	Dec. 31, 2013
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,					Nine months ended
		Years ended December 31,					December 31,
		2013		2012			2011

	Balance, beginning of period	$	6,380	$	4,401	$	1,314
	Warranty assumed on acquisition		582		-		-
	Warranty claims		-5,397		-3,099		-1,395
	Warranty accruals		4,153		5,303		4,530
	Change in estimate		22,837		-		-
	Impact of foreign exchange changes		290		-225		-48
	Balance, end of period	$	28,845	$	6,380	$	4,401

	Less: Current portion		-9,955		-2,072		-1,187

	Long-term portion	$	18,890	$	4,308	$	3,214

Other_longterm_liabilities_Tab

Other long-term liabilities (Tables)	12 Months Ended
Other long-term liabilities (Tables)	Dec. 31, 2013
Other Liabilities Disclosure [Abstract]	'
Schedule of Other Long Term Liabilities [Table Text Block]	'
			December 31,		December 31,
			2013		2012
	Severance indemnity (a)		$	1,547	$	1,681
	Contingent consideration payable related to AFV acquisition (b)			878		856
	Deferred lease inducements			16		69

			$	2,441	$	2,606

		(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 is estimated to have a fair value of $427 as at December 31, 2013 (December 31, 2012 - $442).

Stock_options_and_other_stockb1

Stock options and other stock-based plans (Tables)	12 Months Ended
Stock options and other stock-based plans (Tables)	Dec. 31, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
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, 2013, December 31, 2012 and December 31, 2011 and changes during the periods then ended are presented as follows:

				December 31, 2013					December 31, 2012					December 31, 2011
				Number of			Weighted		Number of shares			Weighted		Number of shares		Weighted
				shares			average					average				average
							exercise					exercise				exercise
							price					price				price
							(CDN $)					(CDN $)				(CDN $)

	Outstanding , beginning of period			996,047		$	27.78		328,027		$	8.96		562,014		$	8.46

	Granted			-			-		770,727			33.77		-			-
	Exercised			-111,986			6.8		-93,044			10.49		-225,845			7.87
	Forfeited/expired			-67,611			33.72		-9,663			33.36		-8,142			4.84

	Outstanding, end of period			816,450		$	30.2		996,047		$	27.78		328,027		$	8.96

	Options exercisable, end of period			305,506		$	24.15		226,487		$	8.06		311,360		$	8.55

Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table Text Block]	'
	As at December 31, 2013, $2,409 of compensation cost related to stock option awards has yet to be recognized in results from operations and will be recognized over a weighted average period of 1.02 years.

	Range of exercise prices (CDN $)						Number		Weighted		Weighted			Number			Weighted
							outstanding,		average		average			exercisable,			average
							December 31,		remaining		exercise			December 31,			exercise
							2013		contractual		price			2013			price
									life		(CDN$)						(CDN $)
	$	3.22	to	$	3.47		5,504		0.5		$	3.29		5,504		$	3.29
		4.24	to		4.27		21,900		0.7			4.27		21,900			4.27
		9.1	to		11.11		79,237		1			10.79		79,237			10.79
		14.9	to		16.5		16,903		1.9			15.69		16,903			15.69
		29.76	to		33.83		692,906		3			33.8		181,962			33.78

	$	3.22	to	$	33.83		816,450		2.7		$	30.2		305,506		$	24.15

Schedule of Performance Share Unit and Restricted Stock Unit 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, 2013, December 31, 2012 and December 31, 2011 are as follows:

			December 31, 2013					December 31, 2012					December 31, 2011
			Number of		Weighted			Number of		Weighted			Number of		Weighted
			units		average			units		average			units		average
					grant					grant					grant
					date fair					date fair					date fair
					value					value					value
					(CDN $)					(CDN $)					(CDN $)

	Outstanding, beginning of period		1,095,094		$	20.68		1,250,917		$	18.04		1,377,237		$	12.19
	Granted		742,140		$	30.21		185,705		$	35.99		269,292		$	35.7
	Exercised/Vested		-448,526		$	24.44		-337,228		$	19.34		-391,612		$	9.61
	Forfeited/expired		-188,117		$	29.8		-4,300		$	19.67		-4,000		$	18.61

	Outstanding, end of period		1,200,591		$	23.68		1,095,094		$	20.68		1,250,917		$	18.04

	Units outstanding and exercisable, end of period		224,638		$	11.2		262,615		$	8.86		276,931		$	7.97

Schedule of Nonvested Share Activity [Table Text Block]	'
			Year ended December 31,					Year ended December					Nine months ended
			2013					31, 2012					December 31, 2011
			Number of		Weighted			Number of		Weighted			Number of		Weighted
			units		average			units		average			units		average
					grant					grant					grant
					date fair					date fair					date fair
					value					value					value
					(CDN $)					(CDN $)					(CDN $)

	Unvested, beginning of period		832,479		$	24.41		973,986		$	20.9		835,703		$	15.62
	Granted		742,140		$	30.16		185,705		$	35.99		269,292		$	35.7
	Vested		-410,549		$	27.34		-322,912		$	21.64		-127,009		$	17.55
	Forfeited		-188,117		$	29.8		-4,300		$	18.61		-4,000		$	18.61

	Unvested, end of period		975,953		$	26.55		832,479		$	24.41		973,986		$	20.9


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, 2013 and 2012 are as follows:

			December 31,				December 31,
			2013				2012
			CDN$				CDN$

	Stock options:
	Outstanding		$	1,337			$	4,219
	Exercisable			1,337				4,137
	Exercised			2,667				2,398

	Share units:
	Outstanding		$	24,960			$	28,823
	Exercisable			4,670				6,912
	Exercised			18,041				15,135

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,						Nine months ended
			2013			2012			December 31, 2011

	Research and development		$	2,195		$	2,251		$	825
	General and administrative			10,201			6,752			3,302
	Sales and marketing			1,887			3,465			2,052

			$	14,283		$	12,468		$	6,179

Research_and_development_expen1

Research and development expenses (Tables)	12 Months Ended
Research and development expenses (Tables)	Dec. 31, 2013
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 are receivable as follows:

							Nine months ended
		Years ended December 31,					December 31,
			2013	2012			2011
	Research and development expenses	$	91,772	$	74,040	$	37,178
	Program funding (note 16)		-640		-842		-604

	Research and development	$	91,132	$	73,198	$	36,574

Income_taxes_Tables

Income taxes (Tables)	12 Months Ended
Income taxes (Tables)	Dec. 31, 2013
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, 2013 (year ended December 31, 2012 – 25%; nine months ended December 31, 2011 – 26.5%) as follows:

								Nine months ended
			Years ended December 31,					December 31,
			2013			2012		2011

	Loss before income taxes	$	-184,537		$	-97,036		$	-46,954

	Expected income tax recovery		-47,979			-24,259			-12,443

	Increase (reduction) in income taxes resulting from:
	Non-deductible stock-based compensation		3,619			3,019			1,642
	Other permanent differences		-2,562			-2,158			87
	Withholding taxes		590			1,187			500
	Change in enacted rates		-			62			189
	Foreign tax rate differences, foreign exchange and other adjustments		3,858			-382			-552
	Non-taxable income from equity investment		-2,851			-3,308			-3,974
	Change in valuation allowance		37,391			27,577			13,391
	Goodwill impairment		8,807			-			-

	Income tax expense (recovery)	$	873		$	1,738		$	-1,160

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, 2013			December 31, 2012
	Deferred income tax assets:
	Net loss carry forwards	$	108,083		$	76,496
	Intangible assets		4,276			1,557
	Property, plant and equipment		5,446			5,703
	Financing and share issuance costs		2,696			3,248
	Warranty liability		5,726			2,013
	Deferred revenue		1,191			1,601
	Inventory		2,017			2,300
	Unrealized foreign exchange		21			595
	Research and development		2,341			2,132
	Other		6,410			3,917

	Total gross deferred income tax assets		138,207			99,562
	Valuation allowance		-126,424			-89,033

	Total deferred income tax assets		11,783			10,529

	Deferred income tax liabilities:
	Intangible assets		9,884			8,784
	Property, plant and equipment		3,132			3,297
	Other		650			575
	Total deferred income tax liabilities		13,666			12,656

	Total net deferred income tax liabilities	$	1,883		$	2,127

	Allocated as follows:
	Current deferred income tax assets		3,109			7,183
	Current deferred income tax liabilities		-468			-65
	Long-term deferred income tax assets		379			-
	Long-term deferred income tax liabilities		-4,903			-9,245
	Total net deferred income tax liabilities	$	-1,883		$	-2,127

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, 2013				December 31, 2012

	Beginning balance		$	89,033		$	61,456
	Additions			37,391			27,639
	Reductions			-			-62

	Ending valuation allowance		$	126,424		$	89,033

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, 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

	Nine months ended December 31, 2011:
	Canada		$	-45,899		$	500		$	-	$	500
	United States			-1,862			95			-		95
	Italy			-1,342			388			-2,205		-1,817
	Other			2,149			45			17		62

			$	-46,954		$	1,028		$	-2,188	$	-1,160

Summary of Operating Loss Carryforwards [Table Text Block]	'
		(e)	The Company has loss carry forwards in the various jurisdictions available to offset future taxable income as follows:

	Expiring in:		2014			2015			2016		2017		2018			2026 and later	Total

	Canada		$	2,018		$	2,358		$	-	$	-	$	-	$	341,701	$	346,077
	Italy			-			-			-		-		-		4,585		4,585
	United States			-			-			-		-		-		31,573		31,573
	Sweden			-			-			-		-		-		9,678		9,678
	Other			-			-			-		1,018		7,017		3,204		11,239

	Total		$	2,018		$	2,358		$	-	$	1,018	$	7,017	$	390,741	$	403,152

Related_party_transactions_Tab

Related party transactions (Tables)	12 Months Ended
Related party transactions (Tables)	Dec. 31, 2013
Related Party Transactions [Abstract]	'
Schedule of Related Party Transactions [Table Text Block]	'
	Cost reimbursements from CWI consisted of the following:

							Nine months ended
		Years ended December 31,					December 31,
		2013		2012			2011

	Research and development	$	178	$	160	$	148
	General and administrative		1,351		2,621		338
	Sales and marketing		4,725		3,683		2,598

		$	6,254	$	6,464	$	3,084

Commitments_and_contingencies_

Commitments and contingencies (Tables)	12 Months Ended
Commitments and contingencies (Tables)	Dec. 31, 2013
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:

	2014	$	4,613
	2015		4,339
	2016		6,331
	2017		6,471
	2018		5,080
	Thereafter		57,322

		$	84,156

Segmented_information_Tables

Segmented information (Tables)	12 Months Ended
Segmented information (Tables)	Dec. 31, 2013
Segment Reporting [Abstract]	'
Schedule of Segment Reporting Information [Table Text Block]	'

							Nine months ended
		Years ended December 31,					December 31,
		2013		2012			2011

	Revenue:
	Applied Technologies	$	93,216	$	91,675	$	55,064
	On-Road Systems		55,090		37,558		20,816
	Off-Road Systems		3,309		3,149		1,635
	Corporate and Technology Investments		12,417		23,244		10,181
	CWI		310,651		198,015		138,844
	WWI		466,580		272,086		84,917
	Total segment revenues		941,263		625,727		311,457
	Less: equity investees' revenue		-777,231		-470,101		-223,761
	Total consolidated revenues	$	164,032	$	155,626	$	87,696

	Net consolidated operating income (loss) excluding depreciation and amortization, losses on impairments, write-downs and disposals, foreign exchange loss (gain), bank charges and other:
	Applied Technologies	$	6,635	$	9,820	$	974
	On-Road Systems		-59,843		-40,937		-27,431
	Off-Road Systems		-14,218		-13,653		-4,401
	Corporate and Technology Investments		-83,546		-50,211		-23,153
	CWI		23,539		35,368		42,832
	WWI		14,496		9,765		4,879
	Total segment operating loss		-112,937		-49,848		-6,300
	Less: equity investees’ operating income		-38,035		-45,133		-47,711
	Net consolidated operating loss excluding depreciation and amortization, losses on impairments, write-downs and disposals, foreign exchange (gain) loss, bank charges and other:		-150,972		-94,981		-54,011

	Depreciation and amortization:
	Applied Technologies		7,838		7,905		5,013
	On-Road Systems		3,186		1,028		94
	Off-Road Systems		450		83		-
	Corporate and Technology Investments		4,814		2,379		1,093

	Losses on impairments, write-downs and disposals
	Applied Technologies		31,564		-		-
	On-Road Systems		9,959		-		-
			57,811		11,395		6,200

	Net consolidated operating loss before foreign exchange (gain) loss, bank charges and other		-208,783		-106,376		-60,211

	Foreign exchange (gain) loss, bank charges and other		-14,573		1,922		-1,136

	Loss before undernoted		-194,210		-108,298		-59,075

	Interest on long-term debt and other income (expenses), net		-3,771		-4,928		-2,337
	Income from investment accounted for by the equity method		13,444		16,190		14,458

	Loss before income taxes	$	-184,537	$	-97,036	$	-46,954

Schedule of Assets by Segment [Table Text Block]	'
							Nine months ended
		Years ended December 31,					December 31,
		2013		2012			2011

	Total additions to long-lived assets excluding business combinations:
	Applied Technologies	$	4,408	$	3,000	$	2,201
	On-Road Systems		15,555		10,306		645
	Off-Road Systems		908		1,481		-
	Corporate and Technology Investments		5,579		16,565		10,400

		$	26,450	$	31,352	$	13,246

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
						Nine months ended
		Years ended December 31,				December 31,
		2013		2012		2011

	Americas (including United States)	42			38	28
	Asia (including China)	11			9	15
	Other (including Italy)	47			53	57

Schedule Of Allocation Of The Total Assets [Table Text Block]	'
	As at December 31, 2013, total long-term investments of $21,872 (December 31, 2012 - $18,544) was allocated to the Corporate segment and $256 (December 31, 2012 - $574) was allocated to the On-Road Systems. Total assets are allocated as follows:

		December 31, 2013		December 31, 2012

	Applied Technologies	$	144,803	$	161,206
	On-Road Systems		111,323		85,401
	Off-Road Systems		6,564		6,556
	Corporate and Technology Investments and unallocated assets		228,981		236,914
	CWI		115,343		69,577
	WWI		131,146		86,997
			738,160		646,651
	Less: equity investees’ total assets		246,489		156,574

	Total consolidated assets	$	491,671	$	490,077

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, 2013		December 31, 2012

	Italy	$	66,918	$	99,099
	Canada		30,713		29,707
	United States		47,322		12,463
	Sweden		322		7,720
	China		8,675		6,524
	Australia		1,360		601
		$	155,310	$	156,114
	Less: equity investees’ long-lived assets		8,117		5,826

	Total consolidated long-lived assets	$	147,193	$	150,288

Financial_instruments_Tables

Financial instruments (Tables)	12 Months Ended
Financial instruments (Tables)	Dec. 31, 2013
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, 2013:

		Carrying		Contractual		< 1 year		1-3 years		4-5 years		>5 years
		amount		cash flows		< 1 year		1-3 years		4-5 years		>5 years

	Accounts payable and accrued liabilities	$	53,523	$	53,523	$	53,523	$	-	$	-	$	-
	Unsecured subordinated debentures ⁽¹⁾		33,847		36,902		36,902		-		-		-
	Senior financing ⁽²⁾		15,941		17,167		4,705		9,999		2,463		-
	Senior revolving financing ⁽³⁾		13,779		14,171		14,171		-		-		-
	Other bank financing		403		403		403		-		-		-
	Other long-term debt		2,043		2,057		696		875		486		-
	Operating lease commitments		-		84,154		4,613		10,670		11,549		57,322
	Royalty payments ⁽⁴⁾		1,269		20,149		1,269		2,538		2,529		13,813

		$	120,805	$	228,526	$	116,332	$	24,082	$	17,027	$	71,135

	(1)Includes interest at 9%.
	(2)Includes interest at 2.8% the rate in effect at December 31, 2013
	(3)Includes interest at 2.8%, the rate in effect at December 31, 2013
	(4)From fiscal 2011 to 2015 inclusive, the Company is obligated to pay annual royalties equal to the greater of $1,269 (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, 2013 is as follows:

		U.S. dollars
	Cash and cash equivalents	$	150,595
	Short-term investments		31,820
	Accounts receivable		16,607
	Accounts payable		8,732

		Euros
	Cash and cash equivalents	€	387

Company_organization_and_opera1

Company organization and operations (Details Textual)	12 Months Ended
	Dec. 31, 2013
	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, 2013	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2012
	Canadian dollar	Canadian dollar	Australian dollar	Australian dollar	Euro	Euro	RMB	RMB	Swedish Krona	Swedish Krona
	CAD	CAD	AUD	AUD	EUR (€)	EUR (€)	CNY	CNY	SEK	SEK
Foreign Currency Exchange Rate, Translation	0.94	1.01	0.89	1.04	1.38	1.32	0.17	0.16	0.16	0.15
Average Foreign Currency Exchange Rate Translation	0.97	1	0.97	1.04	1.33	1.29	0.16	0.16	0.15	0.15

Significant_accounting_policie4

Significant accounting policies (Details 1)	12 Months Ended
Significant accounting policies (Details 1)	Dec. 31, 2013
Buildings [Member]	'
Property, Plant and Equipment, Useful Life	'10 years
Property, Plant and Equipment, Depreciation Methods	'Straight-line
Computer equipment and software [Member]	'
Property, Plant and Equipment, Useful Life	'3 years
Property, Plant and Equipment, Depreciation Methods	'Straight-line
Furniture and fixtures [Member]	'
Property, Plant and Equipment, Useful Life	'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	'8 years
Machinery and equipment [Member] \| Maximum [Member]	'
Property, Plant and Equipment, Useful Life	'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)	1 Months Ended		12 Months Ended
	Mar. 31, 2012	Oct. 31, 2011	Dec. 31, 2013	Dec. 31, 2013
			Minimum [Member]	Maximum [Member]
Finite-Lived Intangible Asset, Useful Life	'8 years	'8 years	'5 years	'20 years

Business_combinations_Details

Business combinations (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2013	Oct. 11, 2011	Oct. 31, 2011	Jul. 02, 2011	Jul. 31, 2011
In Thousands, unless otherwise specified	Dec. 31, 2013	BAF Technologies Inc [Member]	AFV [Member]	AFV [Member]	Emer [Member]	Emer [Member]
Other tangible assets, including cash of $1,178	'	$9,116	'	'	$60,532	'
Property, plant and equipment	'	905	'	'	17,644	'
Intangible assets subject to amortization over 3 to 10 years	'	'	2,638	'	32,954	'
Goodwill	'	18,542	2,701	'	50,774	'
Less: total liabilities	'	-6,594	-3,561	'	'	'
Total net assets acquired	'	'	3,939	'	39,706	'
Payable to Clean Energy	'	2,322	428	'	'	'
Common shares issued	'	24,091	'	'	'	'
Common shares to be issued	'	3,285	'	'	'	'
Business Acquisition, Cost of Acquired Entity, Purchase Price	'	29,698	3,939	'	39,706	'
Cash	'	'	2,558	'	17,607	'
Intangible assets	7,729	7,729	'	'	'	'
Total identifiable assets acquired	'	29,698	'	'	'	'
Total tangible assets, including cash of $8	'	'	2,161	'	'	'
Goodwill	'	18,542	2,701	'	50,774	'
Total assets acquired	'	36,292	7,500	'	161,904	'
Other Liabilities	'	'	'	'	-38,926	'
Long-term debt	'	'	'	'	-83,272	'
Common shares	'	'	$953	$953	$22,099	$22,099

Business_combinations_Details_

Business combinations (Details 1) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013
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]	'
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_1

Business combinations (Details 2) (BAF Technologies Inc [Member], USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
BAF Technologies Inc [Member]	'	'
Revenue	$171,281	$181,972
Net loss	($189,448)	($100,946)

Business_combinations_Details_2

Business combinations (Details 3) (Advanced Engine Components Ltd [Member], USD $)	Mar. 20, 2012
In Thousands, unless otherwise specified	Mar. 20, 2012
Advanced Engine Components Ltd [Member]	'
Consideration allocated to:	'
Total tangible assets	$685
Intangible assets subject to amortization over 8 years	832
Total assets acquired	1,517
Less: total liabilities	-392
Total net assets acquired	$1,125

Business_combinations_Details_3

Business combinations (Details Textual)

1 Months Ended

9 Months Ended

12 Months Ended

1 Months Ended

6 Months Ended

12 Months Ended

1 Months Ended

12 Months Ended

0 Months Ended

1 Months Ended

9 Months Ended

0 Months Ended

1 Months Ended

In Thousands, except Share data, unless otherwise specified

Mar. 31, 2012

Oct. 31, 2011

Jul. 31, 2011

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Jun. 28, 2013

Oct. 11, 2011

Jul. 02, 2011

Dec. 31, 2013

Jun. 28, 2013

Dec. 31, 2013

Jun. 28, 2013

Dec. 31, 2013

Dec. 31, 2012

Mar. 20, 2012

Oct. 11, 2011

Oct. 31, 2011

Dec. 31, 2011

Oct. 11, 2011

Jul. 02, 2011

Jul. 31, 2011

Jul. 02, 2011

Jun. 28, 2013

USD ($)

Minimum [Member]

Maximum [Member]

BAF Technologies Inc [Member]

Clean Energy [Member]

AEC [Member]

AFV [Member]

Emer [Member]

Stock Purchase Agreement [Member]

USD ($)

Minimum [Member]

Maximum [Member]

USD ($)

AUD

USD ($)

CAD

SEK

USD ($)

EUR (€)

BAF Technologies Inc [Member]

Business Acquisition, Percentage of Voting Interests Acquired

100.00%

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

718,485

97,975

33,161

881,860

816,460

Business Acquisition, Share Price

$30.62

$28.74

$25.06

$33.53

29.56

Business Acquisition, Equity Interest Issued or Issuable, Value Assigned

$24,091

$3,285

Payments to Acquire Interest in Subsidiaries and Affiliates, Total

5,000

Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents

1,125

1,082

Fair Value Of Products And Services

2,678

Business Combination Consideration Payable

5,000

Business Combination Consideration Payable In Excess

2,322

Foreign Currency Exchange Rate, Translation

1.04

6.6712

1.45

Business Combination, Acquisition Related Costs

1,683

493

280

Business Acquisitions Purchase Price Allocation Current Assets Cash And Cash Equivalents

1,178

Finite-Lived Intangible Asset, Useful Life

'8 years

'5 years

'20 years

'3 years

'10 years

Noncash or Part Noncash Acquisition, Debt Assumed

1,087

77,000

Repayments of Long-term Debt, Total

420

36,300

53,278

9,947

6,725

Long-term Debt, Total

16,220

667

40,700

Business Acquisition Purchase Price Allocation Assets Acquired Liabilities Assumed

3,939

39,706

Payments to Acquire Businesses, Gross

2,558

17,607

Business Combination, Consideration Transferred, Equity Interests Issued and Issuable

953

22,099

Business Acquisitions Purchase Price Allocation Goodwill Amount

2,701

50,774

Revenue, Net, Total

87,696

164,032

155,626

17,097

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

($45,794)

($185,410)

($98,774)

$3,512

Accounts_receivable_Details

Accounts receivable (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Customer trade receivable	$54,017	$39,754
Government funding receivable	483	541
Due from joint venture (note 21)	3,621	2,127
Other receivables	2,689	1,916
Income tax receivable	77	172
Allowance for doubtful accounts	-1,572	-321
Accounts Receivable Net Current	$59,315	$44,189

Inventories_Details

Inventories (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Purchased parts	$25,616	$25,454
Assembled parts	881	4,870
Work-in-process	9,889	7,516
Finished goods	6,628	7,385
Obsolescence provision	-2,388	-279
Inventory Net	$40,626	$44,946

Inventories_Details_Textual

Inventories (Details Textual) (USD $)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
Inventory Write-down	'	$2,720	'
Inventory Obsolescence	430	2,205	233
Cost of Goods Sold Product	67,093	148,690	102,486
Cost of Goods Sold Parts	$67,093	$148,690	$102,486

Longterm_investments_Details

Long-term investments (Details) (USD $)	Dec. 31, 2013		Dec. 31, 2012
In Thousands, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Long Term Investments	$22,128		$19,118
Weichai Westport Inc [Member]	'		'
Long Term Investments	14,534	[1]	11,275	[1]
Cummins Westport, Inc. [Member]	'		'
Long Term Investments	7,191	[2]	7,126	[2]
Other Equity Accounted for Investees [Member]	'		'
Long Term Investments	$403		$717

[1]	Weichai Westport Inc.: On July 3, 2010, the Company invested $4,316 under an agreement with Weichai Power Co. Ltd. and Hong Kong Peterson (â€œCNGâ€) Equipment Ltd. to form Weichai Westport Inc. (â€œWWIâ€). 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, 2013, the Company recognized its share of WWIâ€™s income of $4,264 (year ended December 31, 2012 - $2,881; nine months ended December 31, 2011 - $1,438), 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, 2013 December 31, 2012 Current assets: Cash and short-term investments $ 4,696 $ 1,145 Accounts receivable 31,967 21,512 Inventory 80,412 55,109 Other current assets 176 1,053 Long-term assets Property, plant and equipment 7,021 4,930 Deferred income tax assets 6,874 3,248 Total assets $ 131,146 $ 86,997 Current liabilities: Accounts payable and accrued liabilities $ 71,345 $ 49,125 Other current liabilities 21,671 12,055 Total liabilities $ 93,016 $ 61,180 Nine months ended Years ended December 31, December 31, 2013 2012 2011 Product revenue $ 466,580 $ 272,086 $ 84,917 Cost of revenue and expenses: Cost of product revenue 429,238 247,299 70,345 Operating expenses 22,846 15,022 9,693 452,084 262,321 80,038 Income before income taxes 14,496 9,765 4,879 Income tax expense 2,315 1,536 1,364 Income for the period $ 12,181 $ 8,229 $ 3,515
[2]	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 (â€œJVAâ€) 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 will now have a term of ten years 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. 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 CWIâ€™s economic performance as set forth in the governing documents. As decision-making at the Board of Directorsâ€™ 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 previously contractually required to provide. For the year ended December 31, 2013, the Company recognized its share of CWIâ€™s income of $9,433 (year ended December 31, 2012 - $13,232; nine months ended December 31, 2011 - $12,958), as income from investment accounted for by the equity method. Assets, liabilities, revenue and expenses of CWI are as follows: December 31, 2013 December 31, 2012 Current assets: Cash and short-term investments $ 73,736 $ 44,371 Accounts receivable 6,699 6,995 Current portion of deferred income tax assets 9,429 7,304 Other current assets 210 225 Long-term assets: Property, plant and equipment 1,096 896 Deferred income tax assets 26,227 9,786 Total assets $ 117,397 $ 69,577 Current liabilities: Current portion of warranty liability $ 18,395 $ 13,317 Current portion of deferred revenue 5,478 3,862 Accounts payable and accrued liabilities 9,826 9,401 33,699 26,580 Long-term liabilities: Warranty liability 49,174 17,501 Deferred revenue 17,815 9,968 Other long-term liabilities 2,400 1,312 69,389 28,781 Total liabilities $ 103,088 $ 55,361 Nine months ended December Years ended December 31, 31, 2013 2012 2011 Product revenue $ 261,012 $ 161,741 $ 114,518 Parts revenue 49,639 36,274 24,326 310,651 198,015 138,844 Cost of revenue and expenses: Cost of product and parts revenue 246,403 136,575 78,837 Research and development 21,522 12,114 6,720 General and administrative 1,348 1,417 796 Sales and marketing 17,839 12,541 9,659 Foreign exchange (gain) loss (7) (18) 17 Bank charges, interest and other 607 472 369 287,712 163,101 96,398 Income before undernoted 22,939 34,914 42,446 Interest and investment income 117 530 297 Income before income taxes 23,056 35,444 42,743 Income tax expense (recovery): Current 24,600 16,362 18,602 Deferred (18,566) (6,517) (1,775) 6,034 9,845 16,827 Income for the period $ 17,022 $ 25,599 $ 25,916

Longterm_investments_Details_1

Long-term investments (Details 1) (Weichai Westport Inc [Member], USD $)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
Weichai Westport Inc [Member]	'	'	'
Current assets:	'	'	'
Cash and short-term investments	'	$4,696	$1,145
Accounts receivable	'	31,967	21,512
Inventory	'	80,412	55,109
Other current assets	'	176	1,053
Long-term assets	'	'	'
Property, plant and equipment	'	7,021	4,930
Deferred income tax assets	'	6,874	3,248
Total assets	'	131,146	86,997
Current liabilities:	'	'	'
Accounts payable and accrued liabilities	'	71,345	49,125
Other current liabilities	'	21,671	12,055
Total liabilities	'	93,016	61,180
Product revenue	84,917	466,580	272,086
Cost of revenue and expenses:	'	'	'
Cost of product revenue	75,581	429,238	247,299
Operating expenses	4,457	22,846	15,022
Equity Method Investment Summarized Financial Information Cost of Revenue and Expensesa	80,038	452,084	262,321
Income before income taxes	4,879	14,496	9,765
Income tax expense	1,364	2,315	1,536
Income for the period	$3,515	$12,181	$8,229

Longterm_investments_Details_2

Long-term investments (Details 2) (Cummins Westport, Inc. [Member], USD $)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
Cummins Westport, Inc. [Member]	'	'	'
Current assets:	'	'	'
Cash and short-term investments	'	$73,736	$44,371
Accounts receivable	'	4,645	6,995
Current portion of deferred income tax assets	'	13,958	7,304
Other current assets	'	210	225
Long-term assets:	'	'	'
Property, plant and equipment	'	1,096	896
Deferred income tax assets	'	21,698	9,786
Current liabilities	'	115,343	69,577
Long-term liabilities	'	'	'
Current portion of warranty liability	'	18,395	13,317
Current portion of deferred revenue	'	5,478	3,862
Accounts payable and accrued liabilities	'	7,772	9,401
Current liabilities	'	31,645	26,580
Long-term liabilities:	'	'	'
Warranty liability	'	49,174	17,501
Deferred revenue	'	17,815	9,968
Other long-term liabilities	'	2,400	1,312
Long-term liabilities	'	69,389	28,781
Total liabilities	'	101,034	55,361
Product revenue	114,518	261,012	161,741
Parts revenue	24,326	49,639	36,274
Total revenue	138,844	310,651	198,015
Cost of revenue and expenses:	'	'	'
Cost of product and parts revenue	78,837	246,403	136,575
Research and development	6,720	21,522	12,114
General and administrative	796	1,348	1,417
Sales and marketing	9,659	17,839	12,541
Foreign exchange loss	17	-7	-18
Bank charges, interest and other	369	607	472
Equity Method Investment Summarized Financial Information Cost of Revenue and Expenses	96,398	287,712	163,101
Income before undernoted	42,446	22,939	34,914
Interest and investment income	297	117	530
Income before income taxes	42,743	23,056	35,444
Income tax expense (recovery)	'	'	'
Current	18,602	24,600	16,362
Deferred	-1,775	-18,566	-6,517
Income tax recovery (expense)	16,827	6,034	9,845
Income for the period	$25,916	$17,022	$25,599

Longterm_investments_Details_T

Long-term investments (Details Textual) (USD $)	1 Months Ended	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Jul. 31, 2010	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
Equity Method Investment, Profit Sharing Percentage	'	'	75.00%	'
Equity Method Investment, Summarized Financial Information, Net Income (Loss) after Attributable to Joint Venture Partner	'	'	$0	$13,232
Payments to Acquire Equity Method Investments	'	955	0	0
Income (Loss) from Equity Method Investments	'	14,458	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)	'	25,916	17,022	25,599
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	'	$1,438	$4,264	$2,881

Variable_Interest_Entities_Det

Variable Interest Entities (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Accounts Receivable [Member]	'	'
Variable Interest Entity [Line Items]	'	'
Variable Interest Entity, Carrying Amount	$3,621	$2,127
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	3,621	2,127
Equity Method Investments [Member]	'	'
Variable Interest Entity [Line Items]	'	'
Variable Interest Entity, Carrying Amount	7,191	7,126
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	$7,191	$7,126

Variable_Interest_Entities_Det1

Variable Interest Entities (Details Textual)	1 Months Ended	12 Months Ended
Variable Interest Entities (Details Textual)	Feb. 20, 2012	Dec. 31, 2013
Variable Interest Entity [Line Items]	'	'
Equity Method Investment, Ownership Percentage	'	50.00%
Description Of Profit Sharing Percentage	75.00%	25.00%

Property_plant_and_equipment_D

Property, plant and equipment (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Cost	$132,818	$112,405
Accumulated depreciation	65,469	54,211
Net book value	67,349	58,194
Land and buildings [Member]	'	'
Cost	532	575
Accumulated depreciation	70	64
Net book value	462	511
Computer equipment and software [Member]	'	'
Cost	12,794	11,529
Accumulated depreciation	9,152	8,140
Net book value	3,642	3,389
Furniture and fixtures [Member]	'	'
Cost	6,414	4,032
Accumulated depreciation	2,408	1,913
Net book value	4,006	2,119
Machinery and equipment [Member]	'	'
Cost	96,656	80,667
Accumulated depreciation	42,439	34,219
Net book value	54,217	46,448
Leasehold improvements [Member]	'	'
Cost	16,422	15,602
Accumulated depreciation	11,400	9,875
Net book value	$5,022	$5,727

Property_plant_and_equipment_D1

Property, plant and equipment (Details Textual) (USD $)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
Depreciation, Total	$4,394	$12,246	$8,131
Machinery and Equipment [Member]	'	'	'
Capital Leased Assets, Gross	'	18,788	16,532
Capital Leases, Balance Sheet, Assets by Major Class, Net, Total	'	$5,465	$2,587

Intangible_assets_Details

Intangible assets (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Cost	$48,151	$41,601
Accumulated amortization	9,807	6,386
Net book value	38,344	35,215
Patents and trademarks [Member]	'	'
Cost	20,974	20,192
Accumulated amortization	2,900	1,758
Net book value	18,074	18,434
Technology [Member]	'	'
Cost	7,468	6,961
Accumulated amortization	2,796	1,901
Net book value	4,672	5,060
Customer contracts [Member]	'	'
Cost	18,447	14,404
Accumulated amortization	3,886	2,709
Net book value	14,561	11,695
Other intangibles [Member]	'	'
Cost	1,262	44
Accumulated amortization	225	18
Net book value	$1,037	$26

Intangible_assets_Details_Text

Intangible assets (Details Textual) (USD $)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
Amortization of Intangible Assets	$1,806	$4,042	$3,264
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	'	3,773	'
Finite-Lived Intangible Assets, Amortization Expense, Year Two	'	3,773	'
Finite-Lived Intangible Assets, Amortization Expense, Year Three	'	3,773	'
Finite-Lived Intangible Assets, Amortization Expense, Year Four	'	3,773	'
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	'	3,773	'
Impairment of Intangible Assets, Finite-lived	0	1,721	0
On Road Segment [Member]	'	'	'
Impairment of Intangible Assets, Finite-lived	'	$1,721	'

Goodwill_Details

Goodwill (Details) (USD $)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
Balance, beginning of period:	'	$56,879	$55,814
Acquisition of BAF (note 4(a))	'	18,542	0
Impairment losses	0	34,964	0
Impact of foreign exchange changes	'	1,043	1,065
Balance, end of period	$55,814	$41,500	$56,879

Goodwill_Details_Textual

Goodwill (Details Textual) (USD $)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
Goodwill, Impairment Loss	$0	$34,964	$0
Applied Technologies Segment [Member]	'	'	'
Goodwill, Impairment Loss	'	30,067	'
On Road Segment [Member]	'	'	'
Goodwill, Impairment Loss	'	$4,897	'

Accounts_payable_and_accrued_l2

Accounts payable and accrued liabilities (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Trade accounts payable	$42,872	$37,956
Accrued payroll	7,937	8,539
Accrued interest	893	961
Income taxes payable	709	876
Other payables	2,381	177
Accounts Payable, Current	$54,792	$48,509

Longterm_debt_Details

Long-term debt (Details) (USD $)	Dec. 31, 2013		Dec. 31, 2012
In Thousands, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Debt and Capital Lease Obligations, Total	$66,013		$80,722
Current portion	-53,025		-28,566
Long-term Debt and Capital Lease Obligations, Total	12,988		52,156
Senior revolving financing [Member]	'		'
Debt and Capital Lease Obligations, Total	13,779		13,185	[1]
Long-term payable [Member]	'		'
Debt and Capital Lease Obligations, Total	0	[2]	9,836	[2]
Other bank financing [Member]	'		'
Debt and Capital Lease Obligations, Total	403	[3]	1,171	[3]
Subordinated debenture [Member]	'		'
Debt and Capital Lease Obligations, Total	33,847	[4]	36,185	[4]
Senior financing [Member]	'		'
Debt and Capital Lease Obligations, Total	15,941	[1]	18,812	[1]
Capital lease obligations [Member]	'		'
Debt and Capital Lease Obligations, Total	$2,043	[5]	$1,533	[5]

[1]	The senior financing agreement bears interest at the 6-month Euribor plus 2.5% or a rate of 2.8% as at December 31, 2013 and its carrying value is recorded at amortized cost using the effective interest rate method. The principal repayment schedule of the remaining senior financing is as follows for the years ended December 31: 2014 $ 4,274 2015 - 2016 4,662 2017 4,856 2018 2,428 $ 16,220 The senior revolving financing facility bears interest at the 6-month Euribor plus 2.5% or a rate of 2.8% as at December 31, 2013 and will be repaid through two principal payments of $6,889 (€5,000) on March 31, 2016 and October 2, 2017. The Company has pledged its interest in Emer as a general guarantee for its senior financing and 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, 2013, the Company is in compliance with all covenants under the financing arrangements.
[2]	On July 2, 2010, the Company acquired OMVL and a portion of the purchase price was payable on the third anniversary of the closing date. The amount was fully repaid on July 1, 2013.
[3]	Other bank financing consists of various unsecured bank financing arrangements that carry rates of interest ranging from 1.01% to 8.00% (2012 - 1.01% to 8.00%) and are payable on maturity dates ranging from June 23, 2014 to June 23, 2017.
[4]	On September 23, 2011, the Company raised $33,847 (CDN$36,000) through the issuance of debentures to Macquarie Private Wealth Inc. (â€œMacquarieâ€) on a private placement basis. The debentures are unsecured and subordinated to senior indebtedness, mature on September 22, 2014, 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, which commenced on March 15, 2012. The debentures are 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 can be redeemed at a price equal to $1,100 per $1,000 principal amount. The Company paid to Macquarie a cash commission equal to 3.85% of the gross proceeds of the offering totaling $1,460, which is included in other assets and amortized over the term of the debentures.
[5]	The Company has capital lease obligations that have initial terms of three to five years at interest rates ranging from 3.07% to 7.32% (2012 - 3.07% to 7.32%). The capital lease obligations require the following minimum annual payments during the respective fiscal years: 2014 $ 696 2015 548 2016 327 2017 319 2018 167 $ 2,057 Amount representing interest (14) $ 2,043

Longterm_debt_Details_1

Long-term debt (Details 1) (USD $)	Dec. 31, 2013	Oct. 11, 2011	Jul. 02, 2011
In Thousands, unless otherwise specified	Dec. 31, 2013	Oct. 11, 2011	Jul. 02, 2011
2014	$4,274	'	'
2015	4,662	'	'
2016	4,856	'	'
2017	2,428	'	'
2018	0	'	'
Long-term Debt	$16,220	$667	$40,700

Longterm_debt_Details_2

Long-term debt (Details 2) (USD $)	Dec. 31, 2013
In Thousands, unless otherwise specified	Dec. 31, 2013
2014	$696
2015	548
2016	327
2017	319
2018	167
Capital Leases, Future Minimum Payments Due	2,057
Amount representing interest	-14
Capital Leases, Future Minimum Payments, Present Value of Net Minimum Payments	$2,043

Longterm_debt_Details_Textual

Long-term debt (Details Textual)

9 Months Ended

12 Months Ended

1 Months Ended

12 Months Ended

In Thousands, unless otherwise specified

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Sep. 30, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

USD ($)

EUR (€)

USD ($)

CAD

Letter of Credit [Member]

Subordinated Debt [Member]

Senior Notes [Member]

Revolving Credit Facility [Member]

Notes Payable to Banks [Member]

Capital Lease Obligations [Member]

USD ($)

CAD

USD ($)

Minimum [Member]

Maximum [Member]

Minimum [Member]

Maximum [Member]

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

9.00%

Long Term Debt, Redemption Price as Ratio of Principal Amount during Specified Period

1,150

Long Term Debt, Redemption Price as Ratio of Principal Amount after Specified Date

1,000

Financing Costs as Percentage of Principal Amount

3.85%

Payments of Debt Issuance Costs

$1,460

Debt Instrument, Description of Variable Rate Basis

'6-month Euribor

Debt Instrument, Interest Rate at Period End

2.80%

Debt Instrument, Periodic Payment, Principal

6,889

5,000

Debt Instrument, Interest Rate During Period

0.75%

1.01%

8.00%

3.07%

7.32%

Capital Lease Obligations, Initial Lease Term

'3 years

'5 years

Line of Credit Facility, Maximum Borrowing Capacity before Increase

30,000

Proceeds from Issuance of Debt

$29,080

$2,450

$33,847

36,000

Debt Instrument, Basis Spread on Variable Rate

2.50%

Warranty_liability_Details

Warranty liability (Details) (USD $)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
Movement in Standard and Extended Product Warranty, Increase (Decrease) [Roll Forward]	'	'	'
Balance, beginning of period	$1,314	$6,380	$4,401
Warranty assumed on acquisition	0	582	0
Warranty claims	-1,395	-5,397	-3,099
Warranty accruals	4,530	4,153	5,303
Change in estimate	0	22,837	0
Impact of foreign exchange changes	-48	290	-225
Balance, end of period	4,401	28,845	6,380
Less: Current portion	-1,187	-9,955	-2,072
Long-term portion	$3,214	$18,890	$4,308

Other_longterm_liabilities_Det

Other long-term liabilities (Details) (USD $)	Dec. 31, 2013		Dec. 31, 2012
In Thousands, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Severance indemnity	$1,547	[1]	$1,681	[1]
Business Acquisition Contingent Consideration Potential Cash Payment	878	[2]	856	[2]
Deferred lease inducements	16		69
OtherLiabilitiesNoncurrent	$2,441		$2,606

[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 employeeâ€™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 Companyâ€™s employees in Italy.
[2]	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 is estimated to have a fair value of $427 as at December 31, 2013 (December 31, 2012 - $442).

Other_longterm_liabilities_Det1

Other long-term liabilities (Details Textual) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Business Acquisition Contingent Consideration At Fair Value One	$427	$442
Business Acquisition Contingent Consideration Number of Employees	2	'
Business Acquisition Contingent Consideration Compensation at Fair Value	$451	$414

Government_assistance_Details_

Government assistance (Details Textual)	9 Months Ended	12 Months Ended			12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013
	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	$604	$640	$842	'	'	'	'	'
Annual Royalties Required to be Paid under Agreement	'	'	'	'	1,269	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	'	'	'	'	12,693	13,500	'	'
Maximum Royalties to be Paid under Agreement	'	'	'	'	26,514	28,200	'	1,000
Royalty Expense	'	'	'	'	1,350	'	1,350	'
Accrued Royalties	'	1,269	1,350	'	'	'	'	'
Payments for Cumulative Royalties under Agreement	'	'	'	6,750	'	'	'	'

Share_capital_Details_Textual

Share capital (Details Textual) (USD $)

0 Months Ended

1 Months Ended

12 Months Ended

9 Months Ended

12 Months Ended

1 Months Ended

In Thousands, except Share data, unless otherwise specified

Feb. 27, 2012

Oct. 31, 2013

Dec. 31, 2013

Dec. 31, 2012

Jun. 28, 2013

Oct. 11, 2011

Jul. 02, 2011

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Jul. 31, 2011

Jul. 02, 2011

Oct. 31, 2011

Oct. 11, 2011

Jun. 28, 2013

Common Stock [Member]

Emer S.P.A [Member]

Alternative Fuel Vehicle Sweden AB [Member]

BAF Technologies Inc [Member]

Stock Issued During Period Shares Net Of Cancellation Upon Exercise Of Stock Options

568,276

721,186

513,490

Stock Issued During Period, Shares, New Issues

6,325,000

6,000,000

6,325,000

Share Price

$43.25

$25.39

Stock Issued During Period, Value, New Issues

$273,556

$152,340

$273,556

$152,340

$273,556

Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs

$8,126

$5,065

$8,126

$5,065

$8,126

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

881,860

33,161

718,485

Business Acquisition, Share Price

$30.62

$28.74

$25.06

$28.74

$33.53

Stock_options_and_other_stockb2

Stock options and other stock-based plans (Details) (Employee Stock Option [Member], CAD)	9 Months Ended	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
Employee Stock Option [Member]	'	'	'
Number of shares	'	'	'
Outstanding , beginning of period	562,014	996,047	328,027
Granted	0	0	770,727
Exercised	-225,845	-111,986	-93,044
Forfeited/expired	-8,142	-67,611	-9,663
Outstanding, end of period	328,027	816,450	996,047
Options exercisable, end of period	311,360	305,506	226,487
Weighted average exercise price	'	'	'
Outstanding, beginning of period Weighted Average Exercise Price	8.46	27.78	8.96
Granted Weighted Average Exercise Price	0	0	33.77
Exercised Weighted Average Exercise Price	7.87	6.8	10.49
Forfeited/expired Weighted Average Exercise Price	4.84	33.72	33.36
Outstanding, end of period Weighted Average Exercise Price	8.96	30.2	27.78
Options exercisable, end of period Weighted Average Exercise Price	8.55	24.15	8.06

Stock_options_and_other_stockb3

Stock options and other stock-based plans (Details 1) (CAD)	12 Months Ended
Stock options and other stock-based plans (Details 1) (CAD)	Dec. 31, 2013
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit	3.22
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit	33.83
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options	816,450
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	'2 years 8 months 12 days
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	30.2
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Exercisable Options	305,506
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	24.15
Range One of Exercise Prices [Member]	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit	3.22
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit	3.47
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options	5,504
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	'6 months
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	3.29
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Exercisable Options	5,504
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	3.29
Range Two of Exercise Prices [Member]	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit	4.24
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit	4.27
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options	21,900
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	'8 months 12 days
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	4.27
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Exercisable Options	21,900
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	4.27
Range Three of Exercise Prices [Member]	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit	9.1
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit	11.11
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options	79,237
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	'1 year
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	10.79
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Exercisable Options	79,237
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	10.79
Range Four of Exercise Prices [Member]	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit	14.9
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit	16.5
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options	16,903
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	'1 year 10 months 24 days
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	15.69
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Exercisable Options	16,903
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	15.69
Range Five of Exercise Prices [Member]	'
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit	29.76
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit	33.83
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options	692,906
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	'3 years
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	33.8
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Exercisable Options	181,962
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	33.78

Stock_options_and_other_stockb4

Stock options and other stock-based plans (Details 2) (Share units [Member], CAD)	9 Months Ended	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
Share units [Member]	'	'	'
Outstanding, beginning of period (in units)	1,377,237	1,095,094	1,250,917
Granted (in units)	269,292	742,140	185,705
Exercised/Vested (in units)	-391,612	-448,526	-337,228
Forfeited/expired (in units)	-4,000	-188,117	-4,300
Outstanding, end of period (in units)	1,250,917	1,200,591	1,095,094
Units outstanding and exercisable, end of period (in units)	276,931	224,638	262,615
Outstanding, beginning of period (in Canadian dollars per share)	12.19	20.68	18.04
Granted (in Canadian dollars per share)	35.7	30.21	35.99
Exercised/Vested (in Canadian dollars per share)	9.61	24.44	19.34
Forfeited/expired (in Canadian dollars per share)	18.61	29.8	19.67
Outstanding, end of period (in Canadian dollars per share)	18.04	23.68	20.68
Units outstanding and exercisable, end of period (in Canadian dollars per share)	7.97	11.2	8.86

Stock_options_and_other_stockb5

Stock options and other stock-based plans (Details 3) (Share units [Member], CAD)	9 Months Ended	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
Share units [Member]	'	'	'
Unvested, beginning of period (in units)	835,703	832,479	973,986
Granted (in units)	269,292	742,140	185,705
Vested (in units)	-127,009	-410,549	-322,912
Forfeited (in units)	-4,000	-188,117	-4,300
Unvested, end of period (in units)	973,986	975,953	832,479
Unvested, beginning of period (in Canadian dollars per share)	15.62	24.41	20.9
Granted (in Canadian dollars per share)	35.7	30.16	35.99
Vested (in Canadian dollars per share)	17.55	27.34	21.64
Forfeited (in Canadian dollars per share)	18.61	29.8	18.61
Unvested, end of period (in Canadian dollars per share)	20.9	26.55	24.41

Stock_options_and_other_stockb6

Stock options and other stock-based plans (Details 4) (CAD)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Employee Stock Option [Member]	'	'
Outstanding	1,337	4,219
Exercisable	1,337	4,137
Exercised	2,667	2,398
Share units [Member]	'	'
Outstanding	24,960	28,823
Exercisable	4,670	6,912
Exercised	18,041	15,135

Stock_options_and_other_stockb7

Stock options and other stock-based plans (Details 5) (USD $)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
Allocated Share-based Compensation Expense	$6,179	$14,283	$12,468
Research and development	'	'	'
Allocated Share-based Compensation Expense	825	2,195	2,251
General and administrative	'	'	'
Allocated Share-based Compensation Expense	3,302	10,201	6,752
Sales and marketing	'	'	'
Allocated Share-based Compensation Expense	$2,052	$1,887	$3,465

Stock_options_and_other_stockb8

Stock options and other stock-based plans (Details Textual) (USD $)	9 Months Ended	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	'	8,000,000	'
Allocated Share-based Compensation Expense	$6,179	$14,283	$12,468
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Exercise Price, Ending Balance	'	'	$35.99
Employee Stock Option [Member]	'	'	'
Allocated Share-based Compensation Expense	352	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	'
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Total	'	2,409	'
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	'	'1 year 7 days	'
Share units [Member]	'	'	'
Allocated Share-based Compensation Expense	5,827	12,189	9,763
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	'	56.16%	'
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate	'	1.17%	'
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Exercise Price, Ending Balance	'	$30.72	'
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Total	'	$16,590	'
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	'	'1 year 10 months 10 days	'
Share Based Compensation Arrangement by Share Based Payment Award Equity Instruments Other than Options Subject to Market and Service Conditions	'	389,685	66,428
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	127,009	410,549	322,912
PSU's [Member]	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	'	54,876	'
PSU's [Member] \| Awards Granted Prior to 1 January 2012 [Member]	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	'	160,674	83,218
Share Based Compensation Arrangement by Share Based Payment Award Payout Factor Percentage	'	0.00%	200.00%

Research_and_development_expen2

Research and development expenses (Details) (USD $)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
Research and development expenses	$37,178	$91,772	$74,040
Program funding (note 16)	-604	-640	-842
Research and development	$36,574	$91,132	$73,198

Income_taxes_Details

Income taxes (Details) (USD $)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
Loss before income taxes	($46,954)	($184,537)	($97,036)
Expected income tax recovery	-12,443	-47,979	-24,259
Increase (reduction) in income taxes resulting from:	'	'	'
Non-deductible stock-based compensation	1,642	3,619	3,019
Other permanent differences	87	-2,562	-2,158
Withholding taxes	500	590	1,187
Change in enacted rates	189	0	62
Foreign tax rate differences, foreign exchange and other adjustments	-552	3,858	-382
Non-taxable income from equity investment	-3,974	-2,851	-3,308
Change in valuation allowance	13,391	37,391	27,577
Goodwill impairment	0	-34,964	0
Total	($1,160)	$873	$1,738

Income_taxes_Details_1

Income taxes (Details 1) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Deferred income tax assets:	'	'	'
Net loss carry forwards	$108,083	$76,496	'
Intangible assets	4,276	1,557	'
Property, plant and equipment	5,446	5,703	'
Financing and share issuance costs	2,696	3,248	'
Warranty liability	5,726	2,013	'
Deferred revenue	1,191	1,601	'
Inventory	2,017	2,300	'
Unrealized foreign exchange	21	595	'
Research and development	2,341	2,132	'
Other	6,410	3,917	'
Total gross deferred income tax assets	138,207	99,562	'
Valuation allowance	-126,424	-89,033	-61,456
Total deferred income tax assets	11,783	10,529	'
Deferred income tax liabilities:	'	'	'
Intangible assets	9,884	8,784	'
Property, plant and equipment	3,132	3,297	'
Other	650	575	'
Total deferred income tax liabilities	13,666	12,656	'
Total net deferred income tax liabilities	1,883	2,127	'
Allocated as follows:	'	'	'
Current deferred income tax assets	3,109	7,183	'
Current deferred income tax liabilities	-468	-65	'
Long-term deferred income tax assets	379	0	'
Long-term deferred income tax liabilities	-4,903	-9,245	'
Total net deferred income tax liabilities	($1,883)	($2,127)	'

Income_taxes_Details_2

Income taxes (Details 2) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Beginning balance	$89,033	$61,456
Additions	37,391	27,639
Reductions	0	-62
Ending valuation allowance	$126,424	$89,033

Income_taxes_Details_3

Income taxes (Details 3) (USD $)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
Net income (loss) before income taxes	($46,954)	($184,537)	($97,036)
Current	-1,028	-1,414	-2,147
Deferred	2,188	541	409
Total	1,160	-873	-1,738
CANADA	'	'	'
Net income (loss) before income taxes	-45,899	-99,188	-93,688
Current	500	444	1,339
Deferred	0	89	53
Total	500	533	1,392
UNITED STATES	'	'	'
Net income (loss) before income taxes	-1,862	-31,019	-1,589
Current	95	56	-62
Deferred	0	-295	0
Total	95	-239	-62
ITALY	'	'	'
Net income (loss) before income taxes	-1,342	-27,247	-318
Current	388	836	775
Deferred	-2,205	-311	25
Total	-1,817	525	800
Other [Member]	'	'	'
Net income (loss) before income taxes	2,149	-27,083	-1,441
Current	45	78	95
Deferred	17	-24	-487
Total	$62	$54	($392)

Income_taxes_Details_4

Income taxes (Details 4) (USD $)	Dec. 31, 2013
In Thousands, unless otherwise specified	Dec. 31, 2013
Operating Loss Carryforwards	$403,152
Expiring in 2014 [Member]	'
Operating Loss Carryforwards	2,018
Expiring in 2015 [Member]	'
Operating Loss Carryforwards	2,358
Expiring in 2016 [Member]	'
Operating Loss Carryforwards	0
Expiring in 2017 [Member]	'
Operating Loss Carryforwards	1,018
Expiring In 2018 [Member]	'
Operating Loss Carryforwards	7,017
Expiring in 2026 and Later [Member]	'
Operating Loss Carryforwards	390,741
CANADA	'
Operating Loss Carryforwards	346,077
CANADA \| Expiring in 2014 [Member]	'
Operating Loss Carryforwards	2,018
CANADA \| Expiring in 2015 [Member]	'
Operating Loss Carryforwards	2,358
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 2026 and Later [Member]	'
Operating Loss Carryforwards	341,701
ITALY	'
Operating Loss Carryforwards	4,585
ITALY \| Expiring in 2014 [Member]	'
Operating Loss Carryforwards	0
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 2026 and Later [Member]	'
Operating Loss Carryforwards	4,585
UNITED STATES	'
Operating Loss Carryforwards	31,573
UNITED STATES \| Expiring in 2014 [Member]	'
Operating Loss Carryforwards	0
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 2026 and Later [Member]	'
Operating Loss Carryforwards	31,573
SWEDEN	'
Operating Loss Carryforwards	9,678
SWEDEN \| Expiring in 2014 [Member]	'
Operating Loss Carryforwards	0
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 2026 and Later [Member]	'
Operating Loss Carryforwards	9,678
Other Jurisdictions [Member]	'
Operating Loss Carryforwards	11,239
Other Jurisdictions [Member] \| Expiring in 2014 [Member]	'
Operating Loss Carryforwards	0
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	1,018
Other Jurisdictions [Member] \| Expiring In 2018 [Member]	'
Operating Loss Carryforwards	7,017
Other Jurisdictions [Member] \| Expiring in 2026 and Later [Member]	'
Operating Loss Carryforwards	$3,204

Income_taxes_Details_Textual

Income taxes (Details Textual)	9 Months Ended	12 Months Ended
Income taxes (Details Textual)	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	26.50%	26.00%	25.00%

Related_party_transactions_Det

Related party transactions (Details) (Cummins Westport, Inc. [Member], USD $)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
Expenses incurred in transactions with related party	$3,084	$6,254	$6,464
Research and development [Member]	'	'	'
Expenses incurred in transactions with related party	148	178	160
General and administrative [Member]	'	'	'
Expenses incurred in transactions with related party	338	1,351	2,621
Sales and marketing [Member]	'	'	'
Expenses incurred in transactions with related party	$2,598	$4,725	$3,683

Related_party_transactions_Det1

Related party transactions (Details Textual) (Cummins Westport Inc [Member], USD $)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
Due from Related Parties	'	$3,621	$2,127
Related Party Transaction, Expenses from Transactions with Related Party	3,084	6,254	6,464
Interest Expense [Member]	'	'	'
Related Party Transaction, Expenses from Transactions with Related Party	$116	$0	$114

Service_and_other_revenue_Deta

Service and other revenue (Details Textual) (USD $)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
License and Services Revenue	$0	$0	$7,923
Sales Revenue, Services, Other	0	1,484	1,414
Maintenance Revenue	10,181	14,547	13,907
Service Revenue Recognized On Achievements Of Certain Milestones	$10,181	$14,547	$13,907

Commitments_and_contingencies_1

Commitments and contingencies (Details) (USD $)	Dec. 31, 2013
In Thousands, unless otherwise specified	Dec. 31, 2013
2014	$4,613
2015	4,339
2016	6,331
2017	6,471
2018	5,080
Thereafter	57,322
Operating Leases, Future Minimum Payments Due	$84,156

Commitments_and_contingencies_2

Commitments and contingencies (Details Textual)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013
	USD ($)	USD ($)	USD ($)	EUR (€)
Operating Leases, Rent Expense, Net, Total	$2,070	$5,675	$4,492	'
Guarantor Obligations, Current Carrying Value	'	$342	'	€ 248

Segmented_information_Details

Segmented information (Details) (USD $)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
Less: equity investees' revenue	($223,761)	($777,231)	($470,101)
Total consolidated revenues	87,696	164,032	155,626
Less: equity investeesâ€™ operating income	-47,711	-38,035	-45,133
Net consolidated operating loss excluding depreciation and amortization, losses on impairments, write-downs and disposals, foreign exchange (gain) loss, bank charges and other:	-54,011	-150,972	-94,981
Depreciation and amortization	6,200	16,288	11,395
Losses on impairments, write-downs and disposals	6,200	57,811	11,395
Net consolidated operating loss before foreign exchange (gain) loss, bank charges and other	-60,211	-208,783	-106,376
Foreign exchange (gain) loss, bank charges and other	-1,136	-14,573	1,922
Loss before undernoted	-59,075	-194,210	-108,298
Income from investment accounted for by the equity method	14,458	13,444	16,190
Loss before income taxes	-46,954	-184,537	-97,036
Applied Technologies [Member]	'	'	'
Total segment revenues	55,064	93,216	91,675
Net segment operating loss	974	6,635	9,820
Depreciation and amortization	5,013	7,838	7,905
Losses on impairments, write-downs and disposals	0	31,564	0
On-Road Systems [Member]	'	'	'
Total segment revenues	20,816	55,090	37,558
Net segment operating loss	-27,431	-59,843	-40,937
Depreciation and amortization	94	3,186	1,028
Losses on impairments, write-downs and disposals	0	9,959	0
Off-Road Systems [Member]	'	'	'
Total segment revenues	1,635	3,309	3,149
Net segment operating loss	-4,401	-14,218	-13,653
Depreciation and amortization	0	450	83
Cummins Westport Inc [Member]	'	'	'
Total segment revenues	138,844	310,651	198,015
Net segment operating loss	42,832	23,539	35,368
Segments Reportable [Member]	'	'	'
Total segment revenues	311,457	941,263	625,727
Net segment operating loss	-6,300	-112,937	-49,848
Interest on long-term debt and other income (expenses), net	-2,337	-3,771	-4,928
Income from investment accounted for by the equity method	14,458	13,444	16,190
Corporate And Technology Investments [Member]	'	'	'
Total segment revenues	10,181	12,417	23,244
Net segment operating loss	-23,153	-83,546	-50,211
Depreciation and amortization	1,093	4,814	2,379
Weichai Westport Inc [Member]	'	'	'
Total segment revenues	84,917	466,580	272,086
Net segment operating loss	$4,879	$14,496	$9,765

Segmented_information_Details_

Segmented information (Details 1) (USD $)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
Applied Technologies [Member]	'	'	'
Total additions to long-lived assets excluding business combinations	$2,201	$4,408	$3,000
On-Road Systems [Member]	'	'	'
Total additions to long-lived assets excluding business combinations	645	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	10,400	5,579	16,565
Segments Reportable [Member]	'	'	'
Total additions to long-lived assets excluding business combinations	$13,246	$26,450	$31,352

Segmented_information_Details_1

Segmented information (Details 2)	9 Months Ended	12 Months Ended
Segmented information (Details 2)	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
Americas including United States [Member]	'	'	'
Concentration Risk, Percentage	28.00%	42.00%	38.00%
Asia including China [Member]	'	'	'
Concentration Risk, Percentage	15.00%	11.00%	9.00%
Other including Italy [Member]	'	'	'
Concentration Risk, Percentage	57.00%	47.00%	53.00%

Recovered_Sheet1

Segmented Information (Details 3) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Assets Excluding Equity Investees Total Assets	$738,160	$646,651
Less: equity investeesâ€™ total assets	246,489	156,574
Total consolidated assets	491,671	490,077
Applied Technologies [Member]	'	'
Assets Excluding Equity Investees Total Assets	144,803	161,206
On-Road Systems [Member]	'	'
Assets Excluding Equity Investees Total Assets	111,323	85,401
Off-Road Systems [Member]	'	'
Assets Excluding Equity Investees Total Assets	6,564	6,556
Corporate and Technology Investments and unallocated assets	'	'
Assets Excluding Equity Investees Total Assets	228,981	236,914
Cummins Westport Inc [Member]	'	'
Assets Excluding Equity Investees Total Assets	115,343	69,577
Weichai Westport Inc [Member]	'	'
Assets Excluding Equity Investees Total Assets	$131,146	$86,997

Segmented_information_Details_2

Segmented information (Details 4) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Capital Assets and Goodwill Excluding Equity Investees Long Lived Assets	$155,310	$156,114
Less: equity investees' long-lived assets	8,117	5,826
Total consolidated long-lived assets	147,193	150,288
ITALY	'	'
Capital Assets and Goodwill Excluding Equity Investees Long Lived Assets	66,918	99,099
CANADA	'	'
Capital Assets and Goodwill Excluding Equity Investees Long Lived Assets	30,713	29,707
UNITED STATES	'	'
Capital Assets and Goodwill Excluding Equity Investees Long Lived Assets	47,322	12,463
SWEDEN	'	'
Capital Assets and Goodwill Excluding Equity Investees Long Lived Assets	322	7,720
CHINA	'	'
Capital Assets and Goodwill Excluding Equity Investees Long Lived Assets	8,675	6,524
AUSTRALIA	'	'
Capital Assets and Goodwill Excluding Equity Investees Long Lived Assets	$1,360	$601

Segmented_information_Details_3

Segmented information (Details Textual) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Goodwill	$41,500	$56,879	$55,814
Long-term Investments, Total	22,128	19,118	'
Applied Technologies [Member]	'	'	'
Goodwill	32,554	51,711	'
On-Road Systems [Member]	'	'	'
Goodwill	18,542	5,168	'
Long-term Investments, Total	256	574	'
Corporate And Technology Investments [Member]	'	'	'
Long-term Investments, Total	$21,872	$18,544	'

Financial_instruments_Details

Financial instruments (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013
Carrying amount	$120,805
Contractual cash flows	228,526
Contractual Obligation, Due in Next Twelve Months	116,332
Contractual Obligation, Due in Second and Third Year	24,082
Contractual Obligation, Due in Fourth and Fifth Year	17,027
Contractual Obligation, Due after Fifth Year	71,135
Accounts Payable and Accrued Liabilities [Member]	'
Carrying amount	53,523
Contractual cash flows	53,523
Contractual Obligation, Due in Next Twelve Months	53,523
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
Unsecured subordinated debentures [Member]	'
Carrying amount	33,847	[1]
Contractual cash flows	36,902	[1]
Contractual Obligation, Due in Next Twelve Months	36,902	[1]
Contractual Obligation, Due in Second and Third Year	0	[1]
Contractual Obligation, Due in Fourth and Fifth Year	0	[1]
Contractual Obligation, Due after Fifth Year	0	[1]
Senior financing [Member]	'
Carrying amount	15,941	[2]
Contractual cash flows	17,167	[2]
Contractual Obligation, Due in Next Twelve Months	4,705	[2]
Contractual Obligation, Due in Second and Third Year	9,999	[2]
Contractual Obligation, Due in Fourth and Fifth Year	2,463	[2]
Contractual Obligation, Due after Fifth Year	0	[2]
Senior revolving financing [Member]	'
Carrying amount	13,779	[3]
Contractual cash flows	14,171	[3]
Contractual Obligation, Due in Next Twelve Months	14,171	[3]
Contractual Obligation, Due in Second and Third Year	0	[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	403
Contractual cash flows	403
Contractual Obligation, Due in Next Twelve Months	403
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
other long-term debt [Member]	'
Carrying amount	2,043
Contractual cash flows	2,057
Contractual Obligation, Due in Next Twelve Months	696
Contractual Obligation, Due in Second and Third Year	875
Contractual Obligation, Due in Fourth and Fifth Year	486
Contractual Obligation, Due after Fifth Year	0
Operating lease commitments [Member]	'
Carrying amount	0
Contractual cash flows	84,154
Contractual Obligation, Due in Next Twelve Months	4,613
Contractual Obligation, Due in Second and Third Year	10,670
Contractual Obligation, Due in Fourth and Fifth Year	11,549
Contractual Obligation, Due after Fifth Year	57,322
Royalty payments [Member]	'
Carrying amount	1,269	[4]
Contractual cash flows	20,149	[4]
Contractual Obligation, Due in Next Twelve Months	1,269	[4]
Contractual Obligation, Due in Second and Third Year	2,538	[4]
Contractual Obligation, Due in Fourth and Fifth Year	2,529	[4]
Contractual Obligation, Due after Fifth Year	$13,813	[4]

[1]	Includes interest at 9%.
[2]	Includes interest at 2.8% the rate in effect at December 31, 2013
[3]	Includes interest at 2.8%, the rate in effect at December 31, 2013
[4]	From fiscal 2011 to 2015 inclusive, the Company is obligated to pay annual royalties equal to the greater of $1,269 (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, 2013	Dec. 31, 2012	Dec. 31, 2011	Mar. 31, 2011	Dec. 31, 2013	Dec. 31, 2013
In Thousands, unless otherwise specified	USD ($)	USD ($)	USD ($)	USD ($)	United States of America, Dollars	Euro Member Countries, Euro
					USD ($)	EUR (€)
Cash and cash equivalents	$178,513	$188,958	$63,285	$131,533	$150,595	€ 387
Short-term investments	32,091	26,902	'	'	31,820	'
Accounts receivable	59,315	44,189	'	'	16,607	'
Accounts payable	$54,792	$48,509	'	'	$8,732	'

Financial_instruments_Details_1

Financial instruments (Details Textual)

12 Months Ended

In Thousands, unless otherwise specified

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

USD ($)

CAD

EUR (€)

USD ($)

Accounts Receivable [Member]

Maximum [Member]

Minimum [Member]

Unsecured subordinated debentures [Member]

Senior financing [Member]

Royalty payments [Member]

Customer Receivable [Member]

Government Grants, Receivable [Member]

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

Maximum [Member]

Minimum [Member]

Credit Concentration Risk [Member]

CAD

USD ($)

CAD

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

$269,919

$260,049

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

210,604

Debt Instrument, Interest Rate at Period End

2.80%

Royalty Guarantees, Commitments, Amount

1,350

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

0.00%

Contractual Obligation, Revenue for Payment of Royalty

13,500

12,693

Contractual Obligations, Annual Royalty Payments

28,189

Concentration Risk, Percentage

88.00%

89.00%

1.00%

11.00%

10.00%

Accounts Receivable, Credit Period

'90 days

'30 days

Concentration Risk, Credit Risk, Financial Instrument, Maximum Exposure

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

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

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

$528

Debt Instrument, Interest Rate During Period

2.50%