Fair Value (Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details) (USD $) In Millions	Apr. 30, 2011		Jul. 31, 2010
Derivative assets	$ 185		$ 163
Total assets	41,988		38,240
Derivative liabilities	22		19
Total liabilities	22		19
Available-for-Sale Investments [Member]
U.S. government securities	19,817		16,612
U.S. government agency securities	8,225	[1]	13,579	[1]
Non-U.S. government and agency securities	2,734	[2]	1,467	[2]
Corporate debt securities	4,406		2,222
Asset-backed securities	130		149
Publicly traded equity securities	1,420		1,251
Available-for-Sale Investments [Member] | Fair Value Inputs (Level 1) [Member]
U.S. government securities
U.S. government agency securities		[1]		[1]
Non-U.S. government and agency securities		[2]		[2]
Corporate debt securities
Asset-backed securities
Publicly traded equity securities	1,420		1,251
Available-for-Sale Investments [Member] | Fair Value Inputs (Level 2) [Member]
U.S. government securities	19,817		16,612
U.S. government agency securities	8,225	[1]	13,579	[1]
Non-U.S. government and agency securities	2,734	[2]	1,467	[2]
Corporate debt securities	4,406		2,222
Asset-backed securities
Publicly traded equity securities
Available-for-Sale Investments [Member] | Fair Value Inputs (Level 3) [Member]
U.S. government securities
U.S. government agency securities		[1]		[1]
Non-U.S. government and agency securities		[2]		[2]
Corporate debt securities
Asset-backed securities	130		149
Publicly traded equity securities
Fair Value Inputs (Level 1) [Member]
Derivative assets
Total assets	6,415		3,772
Derivative liabilities
Total liabilities
Fair Value Inputs (Level 1) [Member] | Cash Equivalents [Member]
Money market funds	4,995		2,521
U.S. government securities
U.S. government agency securities		[1]		[1]
Corporate debt securities
Fair Value Inputs (Level 2) [Member]
Derivative assets	183		160
Total assets	35,441		34,316
Derivative liabilities	22		19
Total liabilities	22		19
Fair Value Inputs (Level 2) [Member] | Cash Equivalents [Member]
Money market funds
U.S. government securities	0		235
U.S. government agency securities	76	[1]	40	[1]
Corporate debt securities	0		1
Fair Value Inputs (Level 3) [Member]
Derivative assets	2		3
Total assets	132		152
Derivative liabilities
Total liabilities
Fair Value Inputs (Level 3) [Member] | Cash Equivalents [Member]
Money market funds
U.S. government securities
U.S. government agency securities		[1]		[1]
Corporate debt securities
Cash Equivalents [Member]
Money market funds	4,995		2,521
U.S. government securities	0		235
U.S. government agency securities	76	[1]	40	[1]
Corporate debt securities	$ 0		$ 1

[1] Includes corporate debt securities that are guaranteed by the FDIC.

[2] Includes corporate debt securities that are guaranteed by non-U.S. governments.