v2.4.0.6

Employee Benefits (Narrative) (Details) (USD $) In Thousands, unless otherwise specified | 12 Months Ended
--- | ---
Dec. 31, 2011 | Dec. 31, 2010 | Dec. 31, 2009
Defined Benefit Plan Disclosure [Line Items] |  |  |
Maximum employee contribution as a percentage of annual compensation | 100.00% |  |
Matching percentage by company of first 4% of employee contribution | 100.00% |  |
Percentage of employee contribution fully matched by company | 4.00% |  |
Length of service required to be eligible for annual retirement contributions (in years) | 1 |  |
Number of subsidiaries company provides post-retirement healthcare benefits to | 2 |  |
Length of time amendment increases pension plan (in years) | 3 |  |
Return on asset assumption | 7.00% |  |
Percentage of investments for long-term growth included in investment strategy | 65.00% |  |
Percentage of investments for short-term growth included in investment strategy | 35.00% |  |
Discretionary range for pension fund trustee included in investment policy | 10.00% |  |
Equity securities, target allocation percentage | 55.00% |  |
Fixed income, target allocation percentage | 45.00% |  |
Matching Of Employee Contribution [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined contribution savings plan expense | $ 4,801 | $ 4,556 | $ 4,450
Annual Retirement Contribution [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined contribution savings plan expense | 5,234 | 5,209 | 5,173
Salaried Pension Plan [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Expected 2011 contributions | 2,862 |  |
Wage Pension Plan [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Expected 2011 contributions | 1,923 |  |
Defined Benefit Plans [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Estimated prior service cost to be amortized from other comprehensive income into net periodic benefit cost during 2012 | 297 |  |
Estimated net loss to be amortized from other comprehensive income into net periodic benefit cost during 2012 | 1,755 |  |
Post-Retirement Healthcare Benefit Plans [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Estimated transition obligation to be amortized from other comprehensive income into net periodic benefit cost during 2012 | 0 |  |
Estimated prior service cost to be amortized from other comprehensive income into net periodic benefit cost during 2012 | 84 |  |
Estimated net loss to be amortized from other comprehensive income into net periodic benefit cost during 2012 | $ (176) |  |
Return on asset assumption |  |  |
Minimum [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Funded status of pension plans | 61.00% |  |
Maximum [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Funded status of pension plans | 80.00% |  |

X
- Definition The amounts in accumulated other comprehensive income related to gains and losses that are not recognized immediately and are expected to be recognized as components of net periodic benefit cost over the next fiscal year that follows the most recent annual statement of financial position presented. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph s -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 158 -Paragraph 7 -Subparagraph 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 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (s) -URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanAmortizationOfNetGainsLosses
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The amounts in accumulated other comprehensive income related to prior service cost or credit expected to be recognized as components of net periodic benefit cost over the next fiscal year that follows the most recent annual statement of financial position presented. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph s -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 158 -Paragraph 7 -Subparagraph 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 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (s) -URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanAmortizationOfNetPriorServiceCostCredit
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The amounts in accumulated other comprehensive income related to transition assets (obligations), origination from the adoption of FAS 87 and 106, expected to be recognized as components of net periodic benefit cost over the next fiscal year that follows the most recent annual statement of financial position presented. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph s -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 158 -Paragraph 7 -Subparagraph 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 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (s) -URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanAmortizationOfNetTransitionAssetObligation
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition An assumption as to the rate of return on plan assets reflecting the average rate of earnings expected on the funds invested or to be invested to provide for the benefits included in the benefit obligation. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(3) -URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 87 -Paragraph 264 -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 Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph j -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 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Expected Long-Term Rate of Return on Plan Assets -URI http://asc.fasb.org/extlink&oid=6512013 -Topic 715 -SubTopic 30 + Details
Name: | us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_DefinedBenefitPlanDisclosureLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The employer's best estimate, as soon as it can be reasonably determined, of contributions expected to be paid to the plan during the next fiscal year beginning after the date of the latest statement of financial position. Estimated contributions may be presented in the aggregate combining (1) contributions required by funding regulations or laws, (2) discretionary contributions, and (3) noncash contributions. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph g -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 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanEstimatedFutureEmployerContributionsInNextFiscalYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Target allocation percentage of investments in equity securities to total plan assets presented on a weighted-average basis as of the measurement date of the latest statement of financial position. + References No definition available. + Details
Name: | us-gaap_DefinedBenefitPlanTargetAllocationPercentageOfAssetsEquitySecurities
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Target allocation percentage in other than debt securities, equity securities, and real estate to total plan assets presented on a weighted-average basis as of the measurement date of the latest statement of financial position. + References No definition available. + Details
Name: | us-gaap_DefinedBenefitPlanTargetAllocationPercentageOfAssetsOther
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount of the cost recognized during the period for defined contribution plans. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 11 -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 715 -SubTopic 70 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6414718&loc=d3e28014-114942 + Details
Name: | us-gaap_DefinedContributionPlanCostRecognized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Defined Benefit Plan, Funded Status, Percentage + References No definition available. + Details
Name: | wlk_DefinedBenefitPlanFundedStatusPercentage
Namespace Prefix: | wlk_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Defined Benefit Plan, Plan Amendment, Period Of Time + References No definition available. + Details
Name: | wlk_DefinedBenefitPlanPlanAmendmentPeriodOfTime
Namespace Prefix: | wlk_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | duration

X
- Definition Defined Benefit Plan, Target Allocation Percentage of Assets, Discretionary Range + References No definition available. + Details
Name: | wlk_DefinedBenefitPlanTargetAllocationPercentageOfAssetsDiscretionaryRange
Namespace Prefix: | wlk_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Defined Benefit Plan, Target Allocation Percentage of Assets, Long-Term + References No definition available. + Details
Name: | wlk_DefinedBenefitPlanTargetAllocationPercentageOfAssetsLongTerm
Namespace Prefix: | wlk_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Defined Benefit Plan, Target Allocation Percentage of Assets, Short-Term + References No definition available. + Details
Name: | wlk_DefinedBenefitPlanTargetAllocationPercentageOfAssetsShortTerm
Namespace Prefix: | wlk_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Eligibility requirements, length of service required for annual retirement contribution + References No definition available. + Details
Name: | wlk_EligibilityRequirementsLengthOfServiceRequiredForAnnualRetirementContribution
Namespace Prefix: | wlk_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Matching Percentage Of Company + References No definition available. + Details
Name: | wlk_MatchingPercentageOfCompany
Namespace Prefix: | wlk_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Maximum Employee Contribution As Percentage Of Annual Compensation + References No definition available. + Details
Name: | wlk_MaximumEmployeeContributionAsPercentageOfAnnualCompensation
Namespace Prefix: | wlk_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of subsidiaries, whose employees meet certain minimum age and service requirements, that are provided post-retirement healthcare benefits by the Company. + References No definition available. + Details
Name: | wlk_NumberOfSubsidiariesCompanyProvidesPostRetirementHealthcareBenefit
Namespace Prefix: | wlk_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage Of Employee Contribution Fully Matched By Company + References No definition available. + Details
Name: | wlk_PercentageOfEmployeeContributionFullyMatchedByCompany
Namespace Prefix: | wlk_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration