Commitments and Contingencies - Contractual Obligations Outstanding (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012
Recorded Unconditional Purchase Obligation [Line Items]
Total unconditional purchase obligations	$ 143
Unconditional purchase obligations, Due in Less Than 1 Year	76
Unconditional purchase obligations, Due in 1-3 Years	62
Unconditional purchase obligations, Due in 3-5 Years	5
Unconditional purchase obligations, Due After 5 Years
Total other long-term obligations	16
Other long-term obligations, Due in Less Than 1 Year	1
Other long-term obligations, Due in 1-3 Years	3
Other long-term obligations, Due in 3-5 Years	4
Other long-term obligations, Due After 5 Years	8
Total contractual obligations	159
Total contractual obligations, Due in Less Than 1 Year	77
Total contractual obligations, Due in 1-3 Years	65
Total contractual obligations, Due in 3-5 Years	9
Total contractual obligations, Due After 5 Years	$ 8