Debt and Interest Expense - Anadarko Additional Information (Detail) (USD $)					6 Months Ended
	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2013 Fair Value Inputs Level 1 and Level 2 [Member] Market Approach Valuation Technique [Member]	Dec. 31, 2012 Fair Value Inputs Level 1 and Level 2 [Member] Market Approach Valuation Technique [Member]	Jun. 30, 2013 Senior Notes, 7 Point 625 Percent, Due 2014 [Member]	Jun. 30, 2013 Senior Notes, 5 Point 750 Percent, Due 2014 [Member]	Jun. 30, 2013 Senior Notes, Zero Coupon due 2036 [Member]	Jun. 30, 2013 Senior Notes, Zero Coupon due 2036, Accreted Value [Member]	Jun. 30, 2013 Five Billion Dollar Facility [Member]
Debt Instrument [Line Items]
Five billion dollar facility									$ 5,000,000,000
Debt instrument, principal amount	15,202,000,000	14,952,000,000			500,000,000	275,000,000
Debt instrument, stated interest rate					7.625%	5.75%
Debt instrument, maturity date					Mar. 15, 2014	Jun. 15, 2014	Oct. 10, 2036
Debt instrument, earliest call date								Oct. 10, 2013
Estimated fair value of total borrowings			$ 15,600,000,000	$ 16,200,000,000