Description of Business and Summary of Significant Accounting Policies (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended			12 Months Ended
	Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2013 Customer Concentration Risk [Member]	Apr. 30, 2012 Customer Concentration Risk [Member]	Apr. 30, 2013 Customer Concentration Risk [Member] Sales Revenue, Services, Net [Member]	Apr. 30, 2012 Customer Concentration Risk [Member] Sales Revenue, Services, Net [Member]	Apr. 30, 2013 Line of Credit [Member] Accounts Receivable [Member]	Jul. 31, 2012 Line of Credit [Member] Accounts Receivable [Member]
Numerator:
Net income from continuing operations	$ 822	$ 736	$ 842	$ 799
Net income (loss) from discontinued operations	0	(2)	32	(11)
Net income	$ 822	$ 734	$ 874	$ 788
Shares used in basic per share amounts:
Weighted average common shares outstanding (shares)	297	295	296	297
Shares used in diluted per share amounts:
Weighted average common shares outstanding (shares)	297	295	296	297
Dilutive common equivalent shares from stock options and restricted stock awards (shares)	7	8	7	9
Dilutive weighted average common shares outstanding (shares)	304	303	303	306
Basic and diluted net income per share:
Basic net income per share from continuing operations (In dollars per share)	$ 2.77	$ 2.50	$ 2.84	$ 2.69
Basic net income (loss) per share from discontinued operations (in dollars per share)	$ 0.00	$ (0.01)	$ 0.11	$ (0.04)
Basic net income per share (in dollars per share)	$ 2.77	$ 2.49	$ 2.95	$ 2.65
Diluted net income per share from continuing operations (in dollars per share)	$ 2.71	$ 2.43	$ 2.78	$ 2.61
Diluted net income (loss) per share from discontinued operations (in dollars per share)	$ 0.00	$ (0.01)	$ 0.11	$ (0.03)
Diluted net income per share (in dollars per share)	$ 2.71	$ 2.42	$ 2.89	$ 2.58
Weighted average stock options and restricted stock units excluded from calculation due to anti-dilutive effect (shares)	3	0	3	3
Number of customers accounted for more than ten percent of concentration risk					0	0	0	0	0	0