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Fair Value of Financial Instruments - Additional Information (Detail) - USD ($)
$ in Thousands
Dec. 31, 2020
Dec. 31, 2019
Fair Value Disclosures [Abstract]    
Estimated fair value of Long-term debt (including current maturities) $ 2,979,266  
Gross amount of company's long term debt 2,926,633  
Carrying amount of company's long term debt $ 2,926,633 $ 3,004,532