Cash, Cash Equivalents, and Marketable Securities Summary of Contractual Maturities of Cash Equivalent and Marketable Fixed Income Securities (Detail) $ in Millions	Jun. 30, 2015 USD ($)
Investments Classified by Contractual Maturity Date [Line Items]
Amortized Cost	$ 9,779
Estimated Fair Value	9,779
Due within one year
Investments Classified by Contractual Maturity Date [Line Items]
Amortized Cost	8,230
Estimated Fair Value	8,230
Due after one year through five years
Investments Classified by Contractual Maturity Date [Line Items]
Amortized Cost	1,218
Estimated Fair Value	1,218
Due after five years through ten years
Investments Classified by Contractual Maturity Date [Line Items]
Amortized Cost	145
Estimated Fair Value	145
Due after ten years
Investments Classified by Contractual Maturity Date [Line Items]
Amortized Cost	186
Estimated Fair Value	$ 186