Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation - Additional Information (Detail)

v2.4.1.9
Stock-Based Compensation - Additional Information (Detail) (USD $)
6 Months Ended 12 Months Ended 6 Months Ended 12 Months Ended
Dec. 31, 2014
Dec. 31, 2014
Jun. 29, 2014
Dec. 31, 2013
Dec. 31, 2012
Jun. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Common stock options available for grant           44,021.264us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
2014 Equity Incentive Plan [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Common stock options available for grant 8,204.254us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
/ us-gaap_PlanNameAxis
= hlm_TwoThousandFourteenEquityIncentivePlanMember
8,204.254us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
/ us-gaap_PlanNameAxis
= hlm_TwoThousandFourteenEquityIncentivePlanMember
       
Common stock options granted   35,817.010us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod
/ us-gaap_PlanNameAxis
= hlm_TwoThousandFourteenEquityIncentivePlanMember
       
Common stock options granted   18,208.5us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
/ us-gaap_PlanNameAxis
= hlm_TwoThousandFourteenEquityIncentivePlanMember
       
Dividend yield   0.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate
/ us-gaap_PlanNameAxis
= hlm_TwoThousandFourteenEquityIncentivePlanMember
       
Risk-free interest rate   2.10%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_PlanNameAxis
= hlm_TwoThousandFourteenEquityIncentivePlanMember
       
Expected volatility   32.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
/ us-gaap_PlanNameAxis
= hlm_TwoThousandFourteenEquityIncentivePlanMember
       
Share based compensation $ 675,000us-gaap_ShareBasedCompensation
/ us-gaap_PlanNameAxis
= hlm_TwoThousandFourteenEquityIncentivePlanMember
         
Unrecognized compensation expense for unvested options 6,110,000us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions
/ us-gaap_PlanNameAxis
= hlm_TwoThousandFourteenEquityIncentivePlanMember
6,110,000us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions
/ us-gaap_PlanNameAxis
= hlm_TwoThousandFourteenEquityIncentivePlanMember
       
Weighted average period required for recognition of compensation expense   4 years 6 months        
2014 Equity Incentive Plan [Member] | Time Based Vesting [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Fair value of option   $ 372.598us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= hlm_TwoThousandFourteenEquityIncentivePlanMember
/ us-gaap_VestingAxis
= hlm_TimeBasedVestingMember
       
2014 Equity Incentive Plan [Member] | Performance Based Stock Option [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Common stock options granted   17,608.5us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
/ us-gaap_PlanNameAxis
= hlm_TwoThousandFourteenEquityIncentivePlanMember
/ us-gaap_StatementEquityComponentsAxis
= hlm_PerformanceBasedStockOptionMember
       
Share based compensation   0us-gaap_ShareBasedCompensation
/ us-gaap_PlanNameAxis
= hlm_TwoThousandFourteenEquityIncentivePlanMember
/ us-gaap_StatementEquityComponentsAxis
= hlm_PerformanceBasedStockOptionMember
       
2014 Equity Incentive Plan [Member] | Minimum [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Expected term   6 years 6 months        
2014 Equity Incentive Plan [Member] | Maximum [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Expected term   6 years 9 months        
Deferred Stock Unit [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Deferred stock units right to receive a cash payment 1,323,000us-gaap_DeferredCompensationArrangementWithIndividualDistributionsPaid
/ us-gaap_AwardTypeAxis
= hlm_DeferredStockUnitMember
1,323,000us-gaap_DeferredCompensationArrangementWithIndividualDistributionsPaid
/ us-gaap_AwardTypeAxis
= hlm_DeferredStockUnitMember
       
Predecessor [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Predecessor's number of shares     44,180us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_StatementScenarioAxis
= us-gaap_PredecessorMember
     
Share based compensation     39,229,000us-gaap_ShareBasedCompensation
/ us-gaap_StatementScenarioAxis
= us-gaap_PredecessorMember
9,006,000us-gaap_ShareBasedCompensation
/ us-gaap_StatementScenarioAxis
= us-gaap_PredecessorMember
714,000us-gaap_ShareBasedCompensation
/ us-gaap_StatementScenarioAxis
= us-gaap_PredecessorMember
 
Deferred stock units right to receive a cash payment     2,893,000us-gaap_DeferredCompensationArrangementWithIndividualDistributionsPaid
/ us-gaap_StatementScenarioAxis
= us-gaap_PredecessorMember
864,000us-gaap_DeferredCompensationArrangementWithIndividualDistributionsPaid
/ us-gaap_StatementScenarioAxis
= us-gaap_PredecessorMember
357,000us-gaap_DeferredCompensationArrangementWithIndividualDistributionsPaid
/ us-gaap_StatementScenarioAxis
= us-gaap_PredecessorMember
 
Employee Stock Option [Member] | Predecessor [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Predecessor's liability     $ 48,517,000hlm_ShareBasedCompensationArrangementByShareBasedPaymentAwardStockOptionLiabilityPriorToCancellation
/ us-gaap_OptionIndexedToIssuersEquityTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_StatementScenarioAxis
= us-gaap_PredecessorMember