Schedule of Interest Income and Interest Expense (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Amounts Related To Interest [Line Items]
Interest expense	$ 181	[1]	$ 179	[1]	$ 358	[1]	$ 362	[1]
Interest income	13	[1]	7	[1]	26	[1]	22	[1]
Capitalized interest costs	$ 4		$ 13		$ 8		$ 19

[1] (a)Interest expense and interest income exclude approximately $11 million and $24 million for the three months and six months ended June 30, 2013 and $12 million and $20 million for the three months and six months ended June 30, 2012, respectively, related to investments in and borrowings from variable interest entities for which the Company has a legal right of offset (see Note 13).