Quarterly report pursuant to Section 13 or 15(d)

Summary of Marketable Securities (Detail)

v3.3.0.814
Summary of Marketable Securities (Detail) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2015
Sep. 30, 2014
Sep. 30, 2015
Sep. 30, 2014
Dec. 31, 2014
Schedule of Marketable Securities [Line Items]          
Trading Securities, Change in Unrealized Holding Gain (Loss) $ 27 $ 0 $ 36 $ 0  
Marketable Securities, Amortized Cost Basis 2,210   2,210   $ 992
Marketable Securities, Gross Unrealized Gain 39   39   2
Marketable Securities, Gross Unrealized Loss (1)   (1)   (2)
Trading Securities 1,495   1,495   430
Total Estimated Fair Value 2,248   2,248   992
Available-for-sale Securities, Amortized Cost Basis 751   751   562
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax 3   3   2
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax (1)   (1)   (2)
Available-for-sale Securities, Current 753   753   562
Trading Securities, Short-term Investments, Amortized Cost 1,459   1,459   430
Trading Securities, Gross Unrealized Gain 36   36   0
Trading Securities, Gross Unrealized Loss 0   0   0
Other debt and equity securities          
Schedule of Marketable Securities [Line Items]          
Trading Securities 446   446   42
Available-for-sale Securities, Amortized Cost Basis 8   8   6
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax 0   0   0
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax 0   0   0
Available-for-sale Securities, Current 8   8   6
Trading Securities, Short-term Investments, Amortized Cost 410   410   42
Trading Securities, Gross Unrealized Gain 36   36   0
Trading Securities, Gross Unrealized Loss 0   0   0
U.S. government and agency debt securities          
Schedule of Marketable Securities [Line Items]          
Available-for-sale Securities, Amortized Cost Basis 327   327   321
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax 2   2   1
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax 0   0   (1)
Available-for-sale Securities, Current 329   329   321
Mortgage and asset-backed debt securities          
Schedule of Marketable Securities [Line Items]          
Available-for-sale Securities, Amortized Cost Basis 77   77   89
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax 0   0   1
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax 0   0   (1)
Available-for-sale Securities, Current 77   77   89
Corporate debt securities          
Schedule of Marketable Securities [Line Items]          
Trading Securities 1,049   1,049   388
Available-for-sale Securities, Amortized Cost Basis 339   339   146
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax 1   1   0
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax (1)   (1)   0
Available-for-sale Securities, Current 339   339   146
Trading Securities, Short-term Investments, Amortized Cost 1,049   1,049   388
Trading Securities, Gross Unrealized Gain 0   0   0
Trading Securities, Gross Unrealized Loss $ 0   $ 0   $ 0