Debt Investment Maturities (Detail) $ in Millions	Dec. 31, 2015 USD ($)
Cost Basis
Due in one year or less	$ 36,522
Due after one year through five years	57,639
Due after five years through 10 years	2,519
Due after 10 years	1,306
Total	97,986
Estimated Fair Value
Due in one year or less	36,479
Due after one year through five years	57,461
Due after five years through 10 years	2,441
Due after 10 years	1,351
Total	$ 97,732