Subsidiary Guarantors (Condensed Consolidating Balance Sheet) (Detail) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
ASSETS
Accounts receivable - related parties	$ 0	$ 0
Other current assets	1,304	546
Oil and natural gas properties, net	11,806	11,086
Property and equipment, net	234	216
Investment in subsidiaries	0	0
Other long-term assets	247	271
Total assets	13,591	12,119
LIABILITIES AND EQUITY
Accounts payable - related parties	0	0
Other current liabilities	766	753
Long-term debt	2,741	2,741
Other long-term liabilities	1,355	1,002
Equity	8,729	7,623
Total liabilities and stockholders' equity	13,591	12,119
Consolidation Eliminations [Member]
ASSETS
Accounts receivable - related parties	(8,347)	(8,655)
Other current assets	0	0
Oil and natural gas properties, net	0	0
Property and equipment, net	0	0
Investment in subsidiaries	(2,831)	(1,989)
Other long-term assets	0	0
Total assets	(11,178)	(10,644)
LIABILITIES AND EQUITY
Accounts payable - related parties	(8,347)	(8,655)
Other current liabilities	0	0
Long-term debt	0	0
Other long-term liabilities	0	0
Equity	(2,831)	(1,989)
Total liabilities and stockholders' equity	(11,178)	(10,644)
Parent Company [Member]
ASSETS
Accounts receivable - related parties	8,986	8,991
Other current assets	167	12
Oil and natural gas properties, net	0	0
Property and equipment, net	0	0
Investment in subsidiaries	2,831	1,989
Other long-term assets	105	11
Total assets	12,089	11,003
LIABILITIES AND EQUITY
Accounts payable - related parties	(639)	(336)
Other current liabilities	46	114
Long-term debt	2,741	2,741
Other long-term liabilities	1,212	861
Equity	8,729	7,623
Total liabilities and stockholders' equity	12,089	11,003
Guarantor Subsidiaries [Member]
ASSETS
Accounts receivable - related parties	(639)	(336)
Other current assets	1,137	534
Oil and natural gas properties, net	11,806	11,086
Property and equipment, net	234	216
Investment in subsidiaries	0	0
Other long-term assets	142	260
Total assets	12,680	11,760
LIABILITIES AND EQUITY
Accounts payable - related parties	8,986	8,991
Other current liabilities	720	639
Long-term debt	0	0
Other long-term liabilities	143	141
Equity	2,831	1,989
Total liabilities and stockholders' equity	$ 12,680	$ 11,760