Supplemental Cash Flow Information (Summary Of Supplemental Cash Flow Information) (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Net cash provided by operating activities included:
Interest paid (net of amounts capitalized)	$ 161		$ 67		$ 5
Net income taxes paid to taxing authorities	1,099	[1]	1,211	[1]	617	[1]
Income taxes paid to Marathon Oil under tax sharing agreement			181
Non-cash investing and financing activities:
Capital lease obligations increase	61		62		26
Non-cash contributions from Marathon Oil(a)	43		0		0
Preferred equity interest received in contract settlement	0		45	[2]	0
Preferred equity interest dividend received in-kind	0		1		0
Acquisitions:
Contingent consideration	600	[3]	0		0
Payable to seller	6	[3]	0		0
Intangible asset acquired	0		3		0
Liability assumed	0		2		0
Marathon Oil Companies [Member]
Non-cash investing and financing activities:
Property, Plant and Equipment contributed by Marathon Oil	0		0		81
Non-cash contributions from Marathon Oil(a)					$ 57	[4]

[1] U.S. and most state income taxes, if incurred, were paid by Marathon Oil for periods prior to the Spinoff. The amount for 2012 includes payments of $181 million for 2011 return period income taxes made to Marathon Oil under our tax sharing agreement, and in return we received an equal amount of tax credits. See Note 25.

[2] See Note 6.

[3] See Note 5.

[4] See Note 7.