2.2.0.25truefalse40101 - Disclosure - Summary of Significant Accounting Policies (Narrative) (Details)truefalseIn Thousands, except Share datafalse1falsefalseUSDfalsefalse1/1/2010 - 12/31/2010 USD ($) USD ($) / shares $Duration_1_1_2010_To_12_31_2010http://www.sec.gov/CIK0001130385duration2010-01-01T00:00:002010-12-31T00:00:00Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170Unit15Dividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0Unit1Standardhttp://www.xbrl.org/2003/instancesharesxbrli0Unit13Standardhttp://www.xbrl.org/2003/instancepurexbrli0USDUSD$2falsefalseUSDfalsefalse12/27/2008 - 12/31/2009 USD ($) USD ($) / shares $Duration_12_27_2008_To_12_31_20095http://www.sec.gov/CIK0001130385duration2008-12-27T00:00:002009-12-31T00:00:00Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170Unit13Standardhttp://www.xbrl.org/2003/instancepurexbrli0Unit15Dividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0Unit1Standardhttp://www.xbrl.org/2003/instancesharesxbrli0USDUSD$3falsefalseUSDfalsefalse12/29/2007 - 12/26/2008 USD ($) USD ($) / shares $Duration_12_29_2007_To_12_26_20082http://www.sec.gov/CIK0001130385duration2007-12-29T00:00:002008-12-26T00:00:00Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170Unit15Dividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0Unit13Standardhttp://www.xbrl.org/2003/instancepurexbrli0Unit1Standardhttp://www.xbrl.org/2003/instancesharesxbrli0USDUSD$4falsefalseUSDfalsefalse11/4/2010 USD ($) $As_Of_11_4_2010http://www.sec.gov/CIK0001130385instant2010-11-04T00:00:000001-01-01T00:00:00Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$5falsefalseUSDfalsefalse9/12/2008 USD ($) $As_Of_9_12_2008http://www.sec.gov/CIK0001130385instant2008-09-12T00:00:000001-01-01T00:00:00Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$6falsefalseUSDfalsefalse12/28/2007 USD ($) USD ($) / shares $As_Of_12_28_20072http://www.sec.gov/CIK0001130385instant2007-12-28T00:00:000001-01-01T00:00:00Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170Unit15Dividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0Unit1Standardhttp://www.xbrl.org/2003/instancesharesxbrli0USDUSD$2false0fwlt_PostiveSettlementsOnProjectsfwltfalsecreditdurationPositive settlements received on projects in the periodfalsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1falsefalsefalse00falsefalsefalsefalsefalse2truefalsefalse2430000024300falsetruefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalse4falsefalsefalse00falsefalsefalsefalsefalse5falsefalsefalse00falsefalsefalsefalsefalse6falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryPositive settlements received on projects in the periodNo authoritative reference available.falsefalsePositive settlements on 2 projects in our Global Engineering and Construction Group3false0fwlt_PostiveSettlementsFromArbitrationAwardsfwltfalsedebitdurationReceipt of payment on a long outstanding arbitration award settled in favor of our subsidiary in our Global Engineering and...falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1falsefalsefalse00falsefalsefalsefalsefalse2truefalsefalse1480000014800falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalse4falsefalsefalse00falsefalsefalsefalsefalse5falsefalsefalse00falsefalsefalsefalsefalse6falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryReceipt of payment on a long outstanding arbitration award settled in favor of our subsidiary in our Global Engineering and Construction GroupNo authoritative reference available.falsefalseReceipt of payment on a long outstanding arbitration award settled in favor of our subsidiary in our Global Engineering and Construction Group4false0us-gaap_CashAndCashEquivalentsAtCarryingValueus-gaaptruedebitinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsefalse10571630001057163falsefalsefalsefalsefalse2truefalsefalse997158000997158falsefalsefalsefalsefalse3truefalsefalse773163000773163falsefalsefalsefalsefalse4falsefalsefalse00falsefalsefalsefalsefalse5falsefalsefalse00falsefalsefalsefalsefalse6truefalsefalse10485440001048544falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryIncludes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the Entity may deposit additional funds at any time and also effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months. Compensating balance arrangements that do not legally restrict the withdrawal or usage of cash amounts may be reported as Cash and Cash Equivalents, while legally restricted deposits held as compensating balances against borrowing arrangements, contracts entered into with others, or company statements of intention with regard to particular deposits should not be reported as cash and cash equivalents.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 7, 26 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 8, 9 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 7 -Footnote 1 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 1 -Article 5 falsefalseCash and cash equivalents5false0fwlt_RegisteredSharesToBeAcquiredAdditionalRepurchaseAuthorizationfwltfalsedebitinstantAdditional U.S. dollar value of outstanding shares that may be purchased under publicly announced share repurchase programfalsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalse4truefalsefalse335000000335000falsefalsefalsefalsefalse5falsefalsefalse00falsefalsefalsefalsefalse6falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryAdditional U.S. dollar value of outstanding shares that may be purchased under publicly announced share repurchase programNo authoritative reference available.falsefalseFoster Wheeler AG's outstanding shares authorized for repurchase under additional authorizations, value6false0fwlt_RegisteredSharesToBeAcquiredInitialRepurchaseAuthorizationfwltfalsecreditinstantInitial U.S. dollar value of outstanding shares that may be purchased under publicly announced share repurchase program...falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalse4falsefalsefalse00falsefalsefalsefalsefalse5truefalsefalse750000000750000falsefalsefalsefalsefalse6falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryInitial U.S. dollar value of outstanding shares that may be purchased under publicly announced share repurchase program approved by the Board of Directors.No authoritative reference available.falsefalseFoster Wheeler AG's outstanding shares authorized for repurchase under the initial repurchase program, value7false0fwlt_RegisteredSharesToBeAcquiredRemainingRepurchaseAuthorizationfwltfalsecreditinstantRemaining U.S. dollar value of outstanding shares that may be purchased under publicly announced share repurchase program...falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse500591000500591falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalse4falsefalsefalse00falsefalsefalsefalsefalse5falsefalsefalse00falsefalsefalsefalsefalse6falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryRemaining U.S. dollar value of outstanding shares that may be purchased under publicly announced share repurchase program approved by the Board of Directors.No authoritative reference available.falsefalseFoster Wheeler AG's outstanding shares authorized for repurchase remaining at the balance sheet date, value8false0us-gaap_OtherInventorySuppliesus-gaaptruedebitinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse1125500011255falsefalsefalsefalsefalse2truefalsefalse96360009636falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalse4falsefalsefalse00falsefalsefalsefalsefalse5falsefalsefalse00falsefalsefalsefalsefalse6falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryCarrying amount as of the balance sheet date of products used directly or indirectly in the manufacturing or production process, which may or may not become part of the final product. May also include items used in the storage, presentation or transportation of physical goods.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 6 -Subparagraph a -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 43 -Chapter 3 -Section A -Paragraph 9 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 43 -Chapter 4 -Paragraph 3 falsefalseInventories9false0fwlt_UnremittedEarningsOfSubsidiariesDeemedToBePermanentlyReinvestedfwltfalsedebitinstantUnremitted earnings of subsidiaries, that have been, or are intended to be, permanently reinvested (and for which no...falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1truefalsefalse383800000383800falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalse4falsefalsefalse00falsefalsefalsefalsefalse5falsefalsefalse00falsefalsefalsefalsefalse6falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryUnremitted earnings of subsidiaries, that have been, or are intended to be, permanently reinvested (and for which no incremental income tax has been provided).No authoritative reference available.falsefalseUnremitted earnings of our subsidiaries, that have been, or are intended to be, permanently reinvested10false0us-gaap_LegalFeesus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsefalse1780000017800falsefalsefalsefalsefalse2truefalsefalse1640000016400falsefalsefalsefalsefalse3truefalsefalse2310000023100falsefalsefalsefalsefalse4falsefalsefalse00falsefalsefalsefalsefalse5falsefalsefalse00falsefalsefalsefalsefalse6falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe amount of expense provided in the period for legal costs incurred on or before the balance sheet date pertaining to resolved, pending or threatened litigation, including arbitration and mediation proceedings.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 5 -Paragraph 9 falsefalseLegal Fees11false0fwlt_ShareBasedCompensationArrangementByShareBasedPaymentAwardRestrictedSharesNonvestedNumberfwltfalsenainstantThe number of outstanding restricted shares for which the employer has issued equity instruments with restrictions that will...falsefalsefalsefalsefalsefalsefalsefalsefalsefalseterselabel1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3truefalsefalse8298082980falsefalsefalsefalsefalse4falsefalsefalse00falsefalsefalsefalsefalse5falsefalsefalse00falsefalsefalsefalsefalse6truefalsefalse165960165960falsefalsefalsefalsefalseSharesxbrli:sharesItemTypesharesThe number of outstanding restricted shares for which the employer has issued equity instruments with restrictions that will be removed upon vesting.No authoritative reference available.falsefalseNon-vested restricted shares12false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://fwc.com/role/disclosuresummaryofsignificantaccountingpoliciesnarrativedetails1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalse4falsefalsefalse00falsefalsefalsefalsefalse5falsefalsefalse00falsefalsefalsefalsefalse6falsefalsefalse00falsefalsefalsefalsefalse7falsefalseUSDtruefalse{us-gaap_StatementGeographicalAxis} : Non-U.S. [Member] 12/31/2010 USD ($) $As_Of_12_31_201021http://www.sec.gov/CIK0001130385instant2010-12-31T00:00:000001-01-01T00:00:00falsefalseNon-U.S. [Member]us-gaap_StatementGeographicalAxisxbrldihttp://xbrl.org/2006/xbrldifwlt_NonUSMemberus-gaap_StatementGeographicalAxisexplicitMemberUnit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$8falsefalseUSDtruefalse{us-gaap_StatementGeographicalAxis} : Non-U.S. [Member] 12/31/2009 USD ($) $As_Of_12_31_200925http://www.sec.gov/CIK0001130385instant2009-12-31T00:00:000001-01-01T00:00:00falsefalseNon-U.S. [Member]us-gaap_StatementGeographicalAxisxbrldihttp://xbrl.org/2006/xbrldifwlt_NonUSMemberus-gaap_StatementGeographicalAxisexplicitMemberUnit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$OthernaNo definition available.No authoritative reference available.falsefalseNon-U.S. [Member]13false0us-gaap_CashAndCashEquivalentsAtCarryingValueus-gaaptruedebitinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1truefalsefalse824938000824938falsetruefalsefalsefalse2truefalsefalse772565000772565falsetruefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalse4falsefalsefalse00falsefalsefalsefalsefalse5falsefalsefalse00falsefalsefalsefalsefalse6falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryIncludes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the Entity may deposit additional funds at any time and also effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months. Compensating balance arrangements that do not legally restrict the withdrawal or usage of cash amounts may be reported as Cash and Cash Equivalents, while legally restricted deposits held as compensating balances against borrowing arrangements, contracts entered into with others, or company statements of intention with regard to particular deposits should not be reported as cash and cash equivalents.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 7, 26 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 8, 9 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 7 -Footnote 1 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 1 -Article 5 falsefalseCash and cash equivalents612Summary of Significant Accounting Policies (Narrative) (Details) (USD $)ThousandsNoRoundingUnKnownUnKnownfalsetrue