Commitments - Other Commitments Lease Payments Table (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Other commitments, expiration date	Dec. 31, 2033
2018	$ 1,267
2019	1,069
2020	968
2021	756
2022	605
Later years	1,437
Total	$ 6,102	[1]

[1] Excludes purchase commitments for jointly owned fields and facilities for which the Company is not the operator.