Segment Information - Sales Revenues by Geographic Area Table (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Revenue from External Customer [Line Items]
Sales revenues	$ 14,867	$ 13,307	$ 13,882
United States [Member]
Revenue from External Customer [Line Items]
Sales revenues	11,290	9,911	10,477
Algeria [Member]
Revenue from External Customer [Line Items]
Sales revenues	2,184	2,182	2,258
Other International [Member]
Revenue from External Customer [Line Items]
Sales revenues	$ 1,393	$ 1,214	$ 1,147