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Stock-Based Compensation (Other Stock Grants) (Details) (USD $)
In Thousands, except Share data, unless otherwise specified
 12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Recognized stock-based compensation expense $ 1,114us-gaap_AllocatedShareBasedCompensationExpense $ 0us-gaap_AllocatedShareBasedCompensationExpense $ 0us-gaap_AllocatedShareBasedCompensationExpense
Other stock grants      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of shares issued   55,919us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod
/ us-gaap_PlanNameAxis
= hsc_OtherStockGrantsMember		  
Recognized stock-based compensation expense   $ 700us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_PlanNameAxis
= hsc_OtherStockGrantsMember		  
Other stock grants | Interim Chief Executive Officer      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of shares issued   27,672us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod
/ us-gaap_PlanNameAxis
= hsc_OtherStockGrantsMember
/ us-gaap_TitleOfIndividualAxis
= us-gaap_ChiefExecutiveOfficerMember