Quarterly report pursuant to Section 13 or 15(d)

Financial Instruments - Summary of Company's Long-Term Debt Instruments at their Carrying Value and Fair Value (Detail)

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Financial Instruments - Summary of Company's Long-Term Debt Instruments at their Carrying Value and Fair Value (Detail) - USD ($)
$ in Thousands
Jun. 30, 2021
Dec. 31, 2020
Debt Instrument [Line Items]    
Carrying value $ 190,393 $ 171,175
Fair value 222,600 189,363
Unsecured Debentures    
Debt Instrument [Line Items]    
Carrying value 56,017 54,905
Fair value 58,923 53,830
Secured Notes    
Debt Instrument [Line Items]    
Carrying value 133,029 115,350
Fair value 162,590 134,609
Other Long Term Debt    
Debt Instrument [Line Items]    
Carrying value 1,347 920
Fair value $ 1,087 $ 924