Property and Equipment (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Property Plant And Equipment [Line Items]
Total property and equipment	$ 7,149,373	$ 7,129,996
Less accumulated depreciation, depletion and impairment	(3,820,585)	(3,721,033)
Property and equipment, net	3,328,788	3,408,963
Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	6,831,966	6,809,129
Oil and natural gas properties
Property Plant And Equipment [Line Items]
Total property and equipment	206,262	201,568
Buildings
Property Plant And Equipment [Line Items]
Total property and equipment	99,388	97,029
Land
Property Plant And Equipment [Line Items]
Total property and equipment	$ 11,757	$ 22,270