Related Party Transactions (Narrative) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 Marathon Oil Companies [Member]	Sep. 30, 2011 Marathon Oil Companies [Member]	Sep. 30, 2012 PFD [Member]	Sep. 30, 2011 PFD [Member]	Sep. 30, 2012 TACE [Member]	Sep. 30, 2012 TAME [Member]	Sep. 30, 2012 Centennial [Member]	Dec. 31, 2011 Centennial [Member]	Sep. 30, 2012 LOOP [Member]	Dec. 31, 2011 LOOP [Member]
Related Party Transaction [Line Items]
Equity method investments, ownership percentage									36.00%	50.00%	50.00%		51.00%
Separation and distribution agreement date of Spinoff			May 25, 2011
Maximum duration of agreement for administrative services with former parent (in years)			1 year
Selling, general and administrative expenses	$ 305	$ 299	$ 944	$ 804		$ 26
Prepaid tariff											14	11		4
Long-term debt payable to related parties - borrowings				7,748				7,748
Long-term debt payable to related parties - repayments				11,366		1,047		10,319
Credit agreement termination date					Apr. 01, 2011		Jun. 30, 2011
Property, plant and equipment additions related to capitalized interest incurred by Marathon Oil on behalf of the company	29	28	95	86		2
Net non-cash capital distributions to Marathon Oil				$ 81		$ 81