Contingencies - Deepwater Horizon Events (Detail) (USD $)								12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2011 Macondo Exploration Well [Member]	Feb. 28, 2014 Deepwater Horizon [Member]	Dec. 31, 2013 Deepwater Horizon [Member] Oil Pollution Act of 1990 [Member]	Feb. 04, 2014 Deepwater Horizon [Member] Oil Pollution Act of 1990 [Member] BP Exploration and Production Inc. [Member]	Dec. 31, 2013 Deepwater Horizon [Member] BP indemnification liability [Member]	Dec. 31, 2011 Deepwater Horizon [Member] BP Settlement Agreement [Member]
Loss Contingencies [Line Items]
Anadarko's nonoperated interest			25.00%
Cash payment for Deepwater Horizon settlement								$ 4,000,000,000
Loss contingency accrual	854,000,000	49,000,000					0
Gross OPA-related environmental costs, excluding amounts BP has already funded, amounts that cannot reasonably be estimated by BP, non-OPA-related fines and penalties, and estimated state and local governmental claims						10,900,000,000
Allocable percentage share of gross OPA-related environmental costs					0.00%
Accrual for environmental loss contingencies	126,000,000	81,000,000			0
Penalties or fines assessed against the Company				$ 0