Debt Investment Maturities (Detail) $ in Millions	Jun. 30, 2017 USD ($)
Cost Basis
Due in one year or less	$ 18,212
Due after one year through five years	102,374
Due after five years through 10 years	6,478
Due after 10 years	999
Total	128,063
Estimated Fair Value
Due in one year or less	18,188
Due after one year through five years	102,168
Due after five years through 10 years	6,504
Due after 10 years	1,019
Total	$ 127,879