Equity-Method Investments (Detail) (Equity Method Investments [Member], USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2007
Schedule of Equity Method Investments [Line Items]
Fair value of oil and gas properties and gathering and processing assets contributed by Anadarko				$ 2,900,000,000
Ownership interest of investee entities	95.00%
Carrying amount of notes payable to affiliates	2,900,000,000			2,900,000,000
Carrying amount of investments	2,800,000,000
Applicable interest rate	1.24%	1.31%
Interest expense on the notes payable	37,000,000	42,000,000	38,000,000
Equity earnings from Anadarko's investments in the investee entities	$ (42,000,000)	$ (43,000,000)	$ (41,000,000)
Maximum [Member]
Schedule of Equity Method Investments [Line Items]
Debt-to-capital ratio covenant	0.67