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Pension and Post-Retirement Benefit Costs (Additional Information) (Details) (USD $)
In Thousands, unless otherwise specified
 3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Salaried Pension Plan    
Defined Benefit Plan Disclosure [Line Items]    
Employer contribution $ 0us-gaap_DefinedBenefitPlanContributionsByEmployer
/ us-gaap_PlanNameAxis
= wlk_SalariedPensionPlanMember		 $ 388us-gaap_DefinedBenefitPlanContributionsByEmployer
/ us-gaap_PlanNameAxis
= wlk_SalariedPensionPlanMember
Estimated future employer contributions for next fiscal year 0us-gaap_DefinedBenefitPlansEstimatedFutureEmployerContributionsInCurrentFiscalYear
/ us-gaap_PlanNameAxis
= wlk_SalariedPensionPlanMember		  
Wage Pension Plan    
Defined Benefit Plan Disclosure [Line Items]    
Employer contribution 112us-gaap_DefinedBenefitPlanContributionsByEmployer
/ us-gaap_PlanNameAxis
= wlk_WagePensionPlanMember		 290us-gaap_DefinedBenefitPlanContributionsByEmployer
/ us-gaap_PlanNameAxis
= wlk_WagePensionPlanMember
Estimated future employer contributions for next fiscal year $ 237us-gaap_DefinedBenefitPlansEstimatedFutureEmployerContributionsInCurrentFiscalYear
/ us-gaap_PlanNameAxis
= wlk_WagePensionPlanMember