Quarterly report pursuant to Section 13 or 15(d)

Summary of Marketable Securities (Detail)

v2.4.0.8
Summary of Marketable Securities (Detail) (USD $)
In Millions, unless otherwise specified
Jun. 30, 2014
Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]    
Cost $ 1,542 $ 582
Available-for-sale Securities, Gross Unrealized Gain(1) 3 2
Available-for-sale Securities, Gross Unrealized Loss(1) 2 4
Total Estimated Fair Value 1,543 580
U.S. government and agency debt securities
    
Schedule of Available-for-sale Securities [Line Items]    
Cost 332 355
Available-for-sale Securities, Gross Unrealized Gain(1) 1 0
Available-for-sale Securities, Gross Unrealized Loss(1) 1 1
Total Estimated Fair Value 332 354
Mortgage and asset-backed debt securities
    
Schedule of Available-for-sale Securities [Line Items]    
Cost 92 76
Available-for-sale Securities, Gross Unrealized Gain(1) 1 1
Available-for-sale Securities, Gross Unrealized Loss(1) 1 2
Total Estimated Fair Value 92 75
Corporate debt securities
    
Schedule of Available-for-sale Securities [Line Items]    
Cost 1,045 146
Available-for-sale Securities, Gross Unrealized Gain(1) 1 1
Available-for-sale Securities, Gross Unrealized Loss(1) 0 1
Total Estimated Fair Value 1,046 146
Other debt and equity securities
    
Schedule of Available-for-sale Securities [Line Items]    
Cost 73 5
Available-for-sale Securities, Gross Unrealized Gain(1) 0 0
Available-for-sale Securities, Gross Unrealized Loss(1) 0 0
Total Estimated Fair Value $ 73 $ 5