Long-Term Debt (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011
Debt Instrument [Line Items]
Line of Credit Facility [Line Items]	$ 20		$ 0
Total	1,610		1,486
Less: current portion	(3)		(32)
Total long-term debt	1,607		1,454
7.25% Senior Notes due 2020
Debt Instrument [Line Items]
Debt carrying amount	400		400
6.375% Senior Notes Due 2022
Debt Instrument [Line Items]
Debt carrying amount	400		0
1.00% Senior Convertible Debentures due 2027
Debt Instrument [Line Items]
Debt carrying amount	0	[1]	25	[1]
3.25% Cash Convertible Senior Notes due 2014
Debt Instrument [Line Items]
Debt face amount	460		460
Debt discount	(48)		(67)
Cash conversion option derivative at fair value	81		49
Debt carrying amount	493		442
Term Loan
Debt Instrument [Line Items]
Debt face amount			619
Debt discount	(1)		0
Debt carrying amount	297		619
Line of Credit Facility [Line Items]	$ 298

[1] (1)The remaining outstanding Debentures were redeemed at par during the first quarter of 2012. See additional information below under 1.00% Senior Convertible Debentures due 2027.