Selected Quarterly Financial Data (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Jul. 31, 2013	Jul. 31, 2012	Apr. 30, 2012	Jan. 31, 2012	Oct. 31, 2011	Apr. 30, 2011	Jan. 31, 2011	Oct. 31, 2010	Jul. 31, 2013	Jul. 31, 2012	Jul. 31, 2011
Quarterly Financial Information Disclosure [Abstract]
Total net revenue	$ 634	$ 567	$ 2,091	$ 884	$ 562	$ 1,839	$ 911	$ 491	$ 4,171	$ 3,808	$ 3,449
Cost of revenue	127	146	145	166	139	154	162	123
All other costs and expenses	567	468	664	634	496	583	556	448
Operating income from continuing operations	(60)	(47)	1,282	84	(73)	1,102	193	(80)	1,233	1,168	1,082
Net income (loss) from continuing operations	(46)	(32)	858	65	(54)	732	119	(55)	823	764	688
Net income (loss) from discontinued operations	30	36	(36)	6	35	2	(1)	(9)	35	28	(54)
Net income	$ (16)	$ 4	$ 822	$ 71	$ (19)	$ 734	$ 118	$ (64)	$ 858	$ 792	$ 634
Basic net income per share from continuing operations	$ (0.15)	$ (0.11)	$ 2.89	$ 0.22	$ (0.18)	$ 2.48	$ 0.40	$ (0.18)	$ 2.78	$ 2.58	$ 2.24
Basic net income (loss) per share from discontinued operations	$ 0.10	$ 0.12	$ (0.12)	$ 0.02	$ 0.12	$ 0.01	$ 0.00	$ (0.03)	$ 0.11	$ 0.09	$ (0.18)
Basic net income per share	$ (0.05)	$ 0.01	$ 2.77	$ 0.24	$ (0.06)	$ 2.49	$ 0.40	$ (0.21)	$ 2.89	$ 2.67	$ 2.06
Diluted net income (loss) per share from continuing operations	$ (0.15)	$ (0.11)	$ 2.83	$ 0.21	$ (0.18)	$ 2.41	$ 0.39	$ (0.18)	$ 2.72	$ 2.51	$ 2.17
Diluted net income (loss) per share from discontinued operations	$ 0.10	$ 0.12	$ (0.12)	$ 0.02	$ 0.12	$ 0.01	$ 0.00	$ (0.03)	$ 0.11	$ 0.09	$ (0.17)
Diluted net income per share	$ (0.05)	$ 0.01	$ 2.71	$ 0.23	$ (0.06)	$ 2.42	$ 0.39	$ (0.21)	$ 2.83	$ 2.60	$ 2.00