Annual report pursuant to Section 13 and 15(d)

Commitments and Contingencies - Additional Information (Detail)

v2.4.1.9
Commitments and Contingencies - Additional Information (Detail) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Loss Contingencies [Line Items]  
Losses up to per occurrence related to product liability, automotive, workers' compensation and general liability $ 250hlm_MaximumAmountOfSelfInsuranceCoverage
Liability recorded for such risk insurance reserves 2,253us-gaap_SelfInsuranceReserve
Aggregate vendors and insurers letters of credit related to product purchases and insurance coverage of product liability, workers' compensation and general liability 3,723us-gaap_LettersOfCreditOutstandingAmount
Group health claims up to annual stop loss limit per participant 200hlm_MaximumAnnualStopLossLimitForEachParticipant
Annual group health insurance claims in excess of expected claims 125.00%hlm_MinimumPercentageOfExpectedClaimsForMaintenanceOfAggregateCoverageForAnnualGroupHealthInsurance
Liability recorded for such group health insurance reserves 2,378hlm_LiabilityRecordedForSuchGroupHealthInsuranceReserves
Maximum [Member]  
Loss Contingencies [Line Items]  
Occurrences in excess for purchased catastrophic coverage 40,000hlm_LossForWhichCatastrophicCoverageHasBeenPurchasedFromThirdPartyInsurers
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Minimum [Member]  
Loss Contingencies [Line Items]  
Occurrences in excess for purchased catastrophic coverage $ 250hlm_LossForWhichCatastrophicCoverageHasBeenPurchasedFromThirdPartyInsurers
/ us-gaap_RangeAxis
= us-gaap_MinimumMember