Related Party Transactions (Purchases From Related Parties) (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Related Party Transaction [Line Items]
Related Party Transaction, Purchases from Related Party	$ 357	$ 280	$ 1,916
Marathon Oil Companies [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Purchases from Related Party	0	0	1,590
Centennial [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Purchases from Related Party	3	7	31
LOOP [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Purchases from Related Party	43	44	66
TAAE [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Purchases from Related Party	24	0	0
TACE [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Purchases from Related Party	130	73	46
TAME [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Purchases from Related Party	131	124	153
Other Equity Method Investees [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Purchases from Related Party	$ 26	$ 32	$ 30