Debt Investment Maturities (Detail) $ in Millions	Sep. 30, 2020 USD ($)
Adjusted Cost Basis
Due in one year or less	$ 35,327
Due after one year through five years	55,735
Due after five years through 10 years	30,786
Due after 10 years	3,000
Debt investments, Adjusted Cost Basis	124,848
Estimated Fair Value
Due in one year or less	35,397
Due after one year through five years	59,048
Due after five years through 10 years	33,870
Due after 10 years	3,185
Total	$ 131,500