Property and Equipment (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Property Plant And Equipment [Line Items]
Total property and equipment	$ 7,128,971	$ 7,282,911
Less accumulated depreciation, depletion and impairment	(3,617,231)	(3,362,203)
Property and equipment, net	3,511,740	3,920,708
Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	6,808,201	6,963,148
Oil and natural gas properties
Property Plant And Equipment [Line Items]
Total property and equipment	201,450	200,923
Buildings
Property Plant And Equipment [Line Items]
Total property and equipment	96,950	96,470
Land
Property Plant And Equipment [Line Items]
Total property and equipment	$ 22,370	$ 22,370