v2.4.0.6

Accounting for derivative instruments and hedging activities (Details 3) (USD $) In Thousands, unless otherwise specified | Dec. 31, 2012 | Dec. 31, 2011
--- | --- | ---
Fair value of derivative instruments |  |
Derivative Assets | $ 20,711 | $ 32,854
Derivative Liabilities | 151,248 | 54,202
Derivative instruments designated as cash flow hedges |  |
Fair value of derivative instruments |  |
Derivative Liabilities | 6,507 | 6,878
Derivative instruments designated as cash flow hedges | Interest rate swaps | Current |  |
Fair value of derivative instruments |  |
Derivative Liabilities | 1,340 | 1,561
Derivative instruments designated as cash flow hedges | Interest rate swaps | Long-term |  |
Fair value of derivative instruments |  |
Derivative Liabilities | 5,167 | 5,317
Derivative instruments not designated as cash flow hedges |  |
Fair value of derivative instruments |  |
Derivative Assets | 20,711 | 32,854
Derivative Liabilities | 144,741 | 47,324
Derivative instruments not designated as cash flow hedges | Interest rate swaps | Current |  |
Fair value of derivative instruments |  |
Derivative Liabilities | 7,261 | 2,587
Derivative instruments not designated as cash flow hedges | Interest rate swaps | Long-term |  |
Fair value of derivative instruments |  |
Derivative Assets | 69 |
Derivative Liabilities | 27,713 | 9,637
Derivative instruments not designated as cash flow hedges | Foreign currency forward contracts | Current |  |
Fair value of derivative instruments |  |
Derivative Assets | 9,456 | 10,630
Derivative Liabilities |  | 224
Derivative instruments not designated as cash flow hedges | Foreign currency forward contracts | Long-term |  |
Fair value of derivative instruments |  |
Derivative Assets | 10,998 | 22,224
Derivative Liabilities |  | 221
Derivative instruments not designated as cash flow hedges | Natural gas swaps | Current |  |
Fair value of derivative instruments |  |
Derivative Liabilities |  | 16,439
Derivative instruments not designated as cash flow hedges | Natural gas swaps | Long-term |  |
Fair value of derivative instruments |  |
Derivative Assets | 117 |
Derivative Liabilities | 3,864 | 18,216
Derivative instruments not designated as cash flow hedges | Gas purchase agreements | Current |  |
Fair value of derivative instruments |  |
Derivative Assets | 71 |
Derivative Liabilities | 24,544 |
Derivative instruments not designated as cash flow hedges | Gas purchase agreements | Long-term |  |
Fair value of derivative instruments |  |
Derivative Liabilities | $ 81,359 |

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- Definition Fair value of derivative asset, presented on a gross basis even when the derivative instrument is subject to master netting arrangements and qualifies for net presentation in the statement of financial position. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 205G -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 133 -Paragraph 44C -Subparagraph a -Clause 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 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4B -Subparagraph (a),(c) -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624163-113959 + Details
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- Definition Fair value of derivative liability, presented on a gross basis even when the derivative instrument is subject to master netting arrangements and qualifies for net presentation in the statement of financial position. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 205G -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 133 -Paragraph 44C -Subparagraph a -Clause 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 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4B -Subparagraph (a),(c) -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624163-113959 + Details
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