Annual report pursuant to Section 13 and 15(d)

Estimated Useful Lives of Assets (Parenthetical) (Detail)

v3.6.0.2
Estimated Useful Lives of Assets (Parenthetical) (Detail) - USD ($)
$ in Thousands
Dec. 31, 2016
Dec. 31, 2015
Property, Plant and Equipment [Line Items]    
Accumulated depreciation and amortization $ 1,355,218 $ 1,182,322
Property Under Capital Lease    
Property, Plant and Equipment [Line Items]    
Accumulated depreciation and amortization $ 175,166 $ 150,968