Debt and Interest Expense - Anadarko (Detail) (USD $)			12 Months Ended			12 Months Ended
	Dec. 31, 2012 Fair Value Inputs Level 1 and Level 2 [Member]	Dec. 31, 2011 Fair Value Inputs Level 1 and Level 2 [Member]	Dec. 31, 2012 Senior Notes, Zero Coupon due 2036, Accreted Value [Member]	Dec. 31, 2006 Senior Notes, Zero Coupon due 2036 [Member]	Dec. 31, 2012 Senior Notes, Zero Coupon due 2036 [Member]	Dec. 31, 2012 Five Billion Dollar Facility [Member]	Dec. 31, 2012 Five Billion Dollar Facility [Member] Minimum [Member] London Interbank Offered Rate [Member]	Dec. 31, 2012 Five Billion Dollar Facility [Member] Maximum [Member] London Interbank Offered Rate [Member]	Dec. 31, 2011 Letter of Credit [Member]
Debt Instrument [Line Items]
Line of credit, maximum borrowing capacity						$ 5,000,000,000
Loan proceeds upon issuing debt				500,000,000
Yield to maturity					5.24%
Debt instrument, earliest call date			Oct. 10, 2013
Total borrowings, fair value	16,200,000,000	17,300,000,000
Line of credit, expiration date						Sep. 02, 2015
Margin added to LIBOR							1.25%	2.50%
Percentage of capital stock of certain wholly owned foreign subsidiaries						65.00%
Letter of credit facility, maximum capacity									$ 400,000,000