Carrying Value of Long-Term Debt of Outstanding (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Debt Instrument [Line Items]
Senior notes, carrying amount	$ 2,611	$ 1,623
Other long-term borrowings	0	36
Total long-term debt	2,611	1,659
$500 Million, 6.45% Due June 1, 2016
Debt Instrument [Line Items]
Senior notes, carrying amount	523	530
$500 Million, 7.20% Due June 15, 2018
Debt Instrument [Line Items]
Senior notes, carrying amount	506	507
$300 Million, 6.30% due August 1, 2018
Debt Instrument [Line Items]
Senior notes, carrying amount	317	319
$600 Million, 3.15% Due December 1, 2022
Debt Instrument [Line Items]
Senior notes, carrying amount	598	0
$250 Million, 8.15% Due June 15, 2038
Debt Instrument [Line Items]
Senior notes, carrying amount	267	267
$400 Million, 4.625% Due December 1, 2042
Debt Instrument [Line Items]
Senior notes, carrying amount	$ 400	$ 0