Cash, Cash Equivalents, and Marketable Securities - Summary of Contractual Maturities of Cash Equivalent and Marketable Fixed Income Securities (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014
Investments Classified by Contractual Maturity Date [Line Items]
Amortized Cost	$ 5,404
Estimated Fair Value	5,410
Due within one year
Investments Classified by Contractual Maturity Date [Line Items]
Amortized Cost	3,598
Estimated Fair Value	3,599
Due after one year through five years
Investments Classified by Contractual Maturity Date [Line Items]
Amortized Cost	1,462
Estimated Fair Value	1,467
Due after five years through ten years
Investments Classified by Contractual Maturity Date [Line Items]
Amortized Cost	126
Estimated Fair Value	126
Due after ten years
Investments Classified by Contractual Maturity Date [Line Items]
Amortized Cost	218
Estimated Fair Value	$ 218