Annual report pursuant to Section 13 and 15(d)

Estimated Useful Lives of Assets (Parenthetical) (Detail)

v3.20.4
Estimated Useful Lives of Assets (Parenthetical) (Detail) - USD ($)
$ in Thousands
Dec. 31, 2020
Dec. 31, 2019
Property, Plant and Equipment [Line Items]    
Accumulated depreciation and amortization $ 1,788,041 $ 1,612,990
Property Under Finance Lease    
Property, Plant and Equipment [Line Items]    
Accumulated depreciation and amortization $ 47,961 $ 36,384