Schedule of Interest Income and Interest Expense (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011
Amounts Related To Interest [Line Items]
Interest expense	$ 179	[1]	$ 150	[1]	$ 362	[1]	$ 300	[1]
Interest income	7	[1]	13	[1]	22	[1]	27	[1]
Capitalized interest costs	$ 13		$ 4		$ 19		$ 8

[1] Interest expense and interest income exclude approximately $12 million and $20 million for the three months and six months ended June 30, 2012, respectively, and $12 million and $26 million for the three months and six months ended June 30, 2011, respectively, related to investments in and borrowings from variable interest entities for which the Company has a legal right of offset (see Note 12).