Environmental Matters (Environmental Remediation Costs) (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
Remediation costs incurred	$ 8	$ 10	$ 15	$ 16
Insurance recoveries received

The charge against earnings in the period for known or estimated future costs arising from requirements to perform environmental remediation activities.

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