Summary of Exit Cost (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2012
Restructuring Cost and Reserve [Line Items]
Balance at December 31, 2011	$ 107
Charges Incurred	31
Cash Payments	(45)
Non-cash Settlements and Accretion	4
Balance at June 30, 2012	97
Termination Benefits
Restructuring Cost and Reserve [Line Items]
Balance at December 31, 2011	12
Charges Incurred	17
Cash Payments	(17)
Balance at June 30, 2012	12
Lease, Contract Obligations And, Other Costs
Restructuring Cost and Reserve [Line Items]
Balance at December 31, 2011	95
Charges Incurred	14
Cash Payments	(28)
Non-cash Settlements and Accretion	4
Balance at June 30, 2012	$ 85