Fair Value Measurements - Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (Fair Value, Measurements, Recurring, USD $) In Millions, unless otherwise specified	Feb. 28, 2015	May 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash	$ 778	$ 780
Assets at Fair Value	5,367	5,149
Cash and Cash Equivalents	3,015	2,220
Investments, Fair Value Disclosure	2,346	2,922
Other Long-term Assets	6	7
Fair Value Measurements Using Level 1 | U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets at Fair Value	1,017	1,137
Cash and Cash Equivalents	75	151
Investments, Fair Value Disclosure	942	986
Other Long-term Assets	0	0
Fair Value Measurements Using Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets at Fair Value	3,566	3,225
Cash and Cash Equivalents	2,162	1,289
Investments, Fair Value Disclosure	1,404	1,936
Other Long-term Assets	0	0
Fair Value Measurements Using Level 2 | Time deposits
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets at Fair Value	341	227
Cash and Cash Equivalents	341	227
Investments, Fair Value Disclosure	0	0
Other Long-term Assets	0	0
Fair Value Measurements Using Level 2 | U.S. Agency securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets at Fair Value	904	1,027
Cash and Cash Equivalents	110	25
Investments, Fair Value Disclosure	794	1,002
Other Long-term Assets	0	0
Fair Value Measurements Using Level 2 | Commercial paper and bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets at Fair Value	785	959
Cash and Cash Equivalents	175	25
Investments, Fair Value Disclosure	610	934
Other Long-term Assets	0	0
Fair Value Measurements Using Level 2 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets at Fair Value	1,536	1,012
Cash and Cash Equivalents	1,536	1,012
Investments, Fair Value Disclosure	0	0
Other Long-term Assets	0	0
Fair Value Measurements Using Level 3 | Non-marketable preferred stock
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets at Fair Value	6	7
Cash and Cash Equivalents	0	0
Investments, Fair Value Disclosure	0	0
Other Long-term Assets	$ 6	$ 7