Acquisitions, Divestitures, and Assets Held for Sale - Assets Held for Sale (Details) (Assets Held For Sale [Member], USD $) In Millions, unless otherwise specified			12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2012 Oil and Gas Exploration and Production Reporting Segment [Member]	Dec. 31, 2013 Oil and Gas Exploration and Production Reporting Segment [Member] Fair Value, Inputs, Level 2 [Member] Market Approach Valuation Technique [Member] Nonrecurring [Member]
Long Lived Assets Held-for-sale [Line Items]
Losses on assets held for sale				$ 704
Long-term assets associated with assets held-for-sale	616
Long-term liabilities associated with assets held for sale	27
Losses on assets held for sale			$ 28