Inventories - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Inventories Net [Line Items]
Percentage inventories valued on a last in, first out (LIFO) basis	35.00%	35.00%
Total inventories valued on an average-cost basis	$ 770	$ 801
Recognition of income caused by partial liquidations of the lower cost LIFO inventory base, gross	1	2	27
Recognition of income caused by partial liquidations of the lower cost LIFO inventory base, after tax	$ 1	$ 1	$ 17

The amount of weighted average cost inventory present at the reporting date when inventory is valued using different valuation methods.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6361739&loc=d3e7789-107766

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 43

-Section A

-Paragraph 9

-Chapter 3

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Name:	us-gaap_WeightedAverageCostInventoryAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant