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Financial instruments and risk management (Tables) | 12 Months Ended
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Mar. 31, 2013
Concentration Risk [Line Items] |
Schedule of financial instruments with carrying amounts that differ from fair values | Financial instruments with carrying amounts that differ from their fair values are as follows:
|  | March 31, 2013 |  |  | March 31, 2012 |
|  | Carrying Amount |  |  | Fair Value |  |  | Carrying Amount |  |  | Fair Value |
Capital lease obligations (i) |  | $ | 41,822 |  |  | $ | 37,369 |  |  | $ | 10,701 |  |  | $ | 10,657 |
Series 1 Debentures (ii) |  | 225,000 |  |  | 220,079 |  |  | 225,000 |  |  | 203,624 |
(i) | The fair values of amounts due under capital leases are based on management estimates which are determined by discounting cash flows required under the instruments at the interest rates currently estimated to be available for instruments with similar terms.
(ii) | The fair value of the Series 1 Debentures is based upon the expected discounted cash flows and the period end market price of similar financial instruments.
Schedule of derivative financial instruments | Financial assets and liabilities measured at fair value net of accrued interest on a recurring basis, all of which are classified as Derivative financial instruments on the Consolidated Balance Sheets are summarized below:
March 31, 2013 |  | Carrying Amount |
Embedded price escalation features in certain long term supplier contracts |  | $ | 6,441 |
Less: current portion |  | (4,261 | )
|  | $ | 2,180 |
March 31, 2012 |  | Carrying Amount |
Embedded price escalation features in certain long term supplier contracts |  | $ | 9,146 |
Less: current portion |  | (3,220 | )
|  | $ | 5,926 |
Schedule of unrealized gains and losses on derivative financial instruments | The unrealized gains and losses on derivative financial instruments is comprised as follows:
Year ended March 31, |  | 2013 |  |  | 2012 |  |  | 2011 |
Unrealized loss on cross-currency and interest rate swaps |  | $ | — |  |  | $ | — |  |  | $ | 2,111 |
Unrealized gain on embedded price escalation features in a long term customer construction contract |  | — |  |  | (5,877 | ) |  | (604 | )
Unrealized (gain) loss on embedded price escalation features in certain long term supplier contracts |  | (2,705 | ) |  | 3,495 |  |  | (3,812 | )
|  | $ | (2,705 | ) |  | $ | (2,382 | ) |  | $ | (2,305 | )
Schedule of non-financial assets measured at fair value on a non-recurring basis | Non-financial assets measured at fair value on a non-recurring basis as at March 31, 2013 and March 31, 2012 in the financial statements are summarized below:
|  | March 31, 2013 |  |  | March 31, 2012 |
|  | Carrying Amount |  |  | Change in Fair Value |  |  | Carrying Amount |  |  | Change in Fair Value |
Assets held for sale |  | $ | 157,464 |  |  | $ | (3,346 | ) |  | $ | 1,841 |  |  | $ | (8,748 | )
Schedule of maximum exposure to credit risk for accounts receivable and unbilled revenue | The Company’s maximum exposure to credit risk for accounts receivable and unbilled revenue is as follows:
|  | March 31, 2013 |  |  | March 31, 2012 |
Trade accounts receivables |  | $ | 93,451 |  |  | $ | 213,051 |
Other receivables |  | 7,018 |  |  | 1,078 |
Total accounts receivable |  | $ | 100,469 |  |  | $ | 214,129 |
Unbilled revenue |  | $ | 56,183 |  |  | $ | 86,859 |
Schedule of trade receivables aging | Payment terms are generally net 30 days. As at March 31, 2013 and March 31, 2012, trade receivables are aged as follows:
|  | March 31, 2013 |  |  | March 31, 2012 |
Not past due |  | $ | 76,646 |  |  | $ | 166,362 |
Past due 1-30 days |  | 14,203 |  |  | 27,617 |
Past due 31-60 days |  | 957 |  |  | 8,476 |
More than 61 days |  | 1,645 |  |  | 10,596 |
Total |  | $ | 93,451 |  |  | $ | 213,051 |
Schedule of changes to the allowance for uncollectible accounts | The allowance is an estimate of the March 31, 2013 trade receivable balances that are considered uncollectible. Changes to the allowance are as follows:
Year ended March 31, |  | 2013 |  |  | 2012 |  |  | 2011 |
Opening balance |  | $ | 210 |  |  | $ | 30 |  |  | $ | 1,691 |
Payments received on provided balances |  | (1 | ) |  | — |  |  | (682 | )
Current year allowance |  | 365 |  |  | 180 |  |  | 518 |
Write-offs |  | (574 | ) |  | — |  |  | (1,497 | )
Ending balance |  | $ | — |  |  | $ | 210 |  |  | $ | 30 |
Total revenues |
Concentration Risk [Line Items] |
Schedule of major customers | The following customers accounted for 10% or more of total revenues:
Year ended March 31, |  | 2013 |  |  | 2012 |  |  | 2011 |
Customer A |  | 25 | % |  | 15 | % |  | 30 | %
Customer B |  | 23 | % |  | 23 | % |  | 10 | %
Customer C |  | 17 | % |  | 6 | % |  | — |
Customer D |  | 8 | % |  | 10 | % |  | 13 | %
Customer E |  | 6 | % |  | 31 | % |  | 38 | %
Accounts receivable and unbilled revenue |
Concentration Risk [Line Items] |
Schedule of major customers | At March 31, 2013 and March 31, 2012, the following customers represented 10% or more of accounts receivable and unbilled revenue:
|  | March 31, 2013 |  |  | March 31, 2012 |
Customer A |  | 23 | % |  | 4 | %
Customer B |  | 20 | % |  | 31 | %
Customer C |  | 11 | % |  | 10 | %
Customer D |  | 11 | % |  | 4 | %
Customer E |  | 8 | % |  | 11 | %

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- Definition Tabular disclosure of assets and liabilities by class, including financial instruments measured at fair value that are classified in shareholders' equity, if any, that are measured at fair value on a nonrecurring basis in periods after initial recognition (for example, impaired assets). Disclosures may include, but are not limited to: (a) the fair value measurements recorded and the reasons for the measurements and (b) the level within the fair value hierarchy in which the fair value measurements are categorized in their entirety (levels 1, 2, 3). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 157 -Paragraph 33 -Subparagraph a, b -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19296-110258 + Details
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- Definition Tabular disclosure of the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments, assets, and liabilities. Such certain disclosures about the financial instruments, assets, and liabilities include: (1) the fair value of the required items together with their carrying amounts (as appropriate) and (2) the methodology and assumptions used in developing such estimates of fair value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 107 -Paragraph 14 -Subparagraph a -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 159 -Paragraph 18 -Subparagraph c(2), d, e, f -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13433-108611 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 107 -Paragraph 15 -Subparagraph b-d -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13467-108611 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 159 -Paragraph 19 -Subparagraph a, b, c(1), d(1) -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258 Reference 8: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6447952&loc=d3e13220-108610 Reference 9: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 157 -Paragraph 32 -Subparagraph a, c(1), c(2), c(3), d -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 10: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 107 -Paragraph 10 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 11: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13476-108611 Reference 12: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 30 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14172-108612 + Details
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- Definition Tabular disclosure of all significant concentrations of risk, including credit risk and market risk, arising from all financial instruments (as defined), whether from an individual counterparty or groups of counterparties. The disclosure concerning concentrations of risk may consist of the following information: (1) for concentrations of credit risk disclosure may include: (a) information about the (shared) activity, region, or economic characteristic that identifies the concentration, (b) the maximum amount of loss due to credit risk that, based on the gross fair value of the financial instrument, the entity would incur if parties to the financial instruments that make up the concentration failed completely to perform according to the terms of the contracts and the collateral or other security, if any, for the amount due proved to be of no value to the entity, (c) the policy of requiring collateral or other security to support financial instruments subject to credit risk, information about the entity's access to that collateral or other security, and the nature and a brief description of the collateral or other security supporting those financial instruments, and (d) the policy of entering into master netting arrangements to mitigate the credit risk of financial instruments, information about the arrangements for which the entity is a party, and a brief description of the terms of those arrangements, including the extent to which they would reduce the entity's maximum amount of loss due to credit risk and (2) for disclosure of quantitative information about the market risks of financial instruments that is consistent with the way the company manages or adjusts those risks, disclosure may include: (a) more details about current positions and perhaps activity during the period, (b) the hypothetical effects on comprehensive income (or net assets), or annual income, of several possible changes in market prices, (c) a gap analysis of interest rate re-pricing or maturity dates, (d) the duration of the financial instruments, (e) the entity's value at risk from derivatives and from other positions at the end of the reporting period and the average value at risk during the year, or (f) other ways of reporting quantitative information as internally developed. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 23 -URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13587-108611 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 107 -Paragraph 15A, 15B, 15C, 15D -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13531-108611 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 21 -URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13537-108611 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 22 -URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13572-108611 + Details
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