Acquisitions and Investments (Fair Value of Consideration Transferred) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012	Dec. 31, 2011
Business Acquisition [Line Items]
Cash	$ 1,515		$ 190	$ 74
Fair value of contingent consideration as of acquisition date	600	[1]	0	0
Payable to seller	6	[1]	0	0
Galveston Bay Refinery And Related Assets [Member]
Business Acquisition [Line Items]
Cash	1,491
Fair value of contingent consideration as of acquisition date	600
Payable to seller	6
Post-closing adjustment	(9)
Total consideration	$ 2,088

[1] See Note 5.