Annual report pursuant to Section 13 and 15(d)

Fair Value Measurements - Fair Value of Company's Fixed Rate Senior Notes and Junior Subordinated Debentures (Parenthetical) (Detail)

v2.4.1.9
Fair Value Measurements - Fair Value of Company's Fixed Rate Senior Notes and Junior Subordinated Debentures (Parenthetical) (Detail)
Dec. 31, 2014
Dec. 31, 2013
6.375% Senior Notes [Member]    
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]    
Interest rate on Senior Notes 6.375%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_LongtermDebtTypeAxis
= hlm_SixPointThreeSevenFivePercentSeniorNotesMember
6.375%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_LongtermDebtTypeAxis
= hlm_SixPointThreeSevenFivePercentSeniorNotesMember
10.875% Senior Notes [Member]    
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]    
Interest rate on Senior Notes 10.875%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_LongtermDebtTypeAxis
= hlm_TenPointEightSevenFivePercentageSeniorNotesMember
10.875%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_LongtermDebtTypeAxis
= hlm_TenPointEightSevenFivePercentageSeniorNotesMember