Selected Quarterly Financial Data (Unaudited) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Jul. 31, 2014	Apr. 30, 2014	Jan. 31, 2014	Oct. 31, 2013	Jul. 31, 2013	Apr. 30, 2013	Jan. 31, 2013	Oct. 31, 2012	Jul. 31, 2014	Jul. 31, 2013	Jul. 31, 2012
Quarterly Financial Information Disclosure [Abstract]
Total net revenue	$ 714	$ 2,388	$ 782	$ 622	$ 634	$ 2,091	$ 884	$ 562	$ 4,506	$ 4,171	$ 3,808
Cost of revenue	179	170	176	143	127	145	166	139
All other costs and expenses	592	724	652	556	567	664	634	496
Operating income from continuing operations	(57)	1,494	(46)	(77)	(60)	1,282	84	(73)	1,314	1,233	1,168
Net income (loss) from continuing operations	(29)	984	(37)	(57)	(46)	858	65	(54)	861	823	764
Net income from discontinued operations	0	0	0	46	30	(36)	6	35	46	35	28
Net income	$ (29)	$ 984	$ (37)	$ (11)	$ (16)	$ 822	$ 71	$ (19)	$ 907	$ 858	$ 792
Basic net income per share from continuing operations	$ (0.10)	$ 3.47	$ (0.13)	$ (0.20)	$ (0.15)	$ 2.89	$ 0.22	$ (0.18)	$ 3.02	$ 2.78	$ 2.58
Basic net income per share from discontinued operations	$ 0.00	$ 0.00	$ 0.00	$ 0.16	$ 0.10	$ (0.12)	$ 0.02	$ 0.12	$ 0.16	$ 0.11	$ 0.09
Basic net income per share	$ (0.10)	$ 3.47	$ (0.13)	$ (0.04)	$ (0.05)	$ 2.77	$ 0.24	$ (0.06)	$ 3.18	$ 2.89	$ 2.67
Diluted net income (loss) per share from continuing operations	$ (0.10)	$ 3.39	$ (0.13)	$ (0.20)	$ (0.15)	$ 2.83	$ 0.21	$ (0.18)	$ 2.96	$ 2.72	$ 2.51
Diluted net income per share from discontinued operations	$ 0.00	$ 0.00	$ 0.00	$ 0.16	$ 0.10	$ (0.12)	$ 0.02	$ 0.12	$ 0.16	$ 0.11	$ 0.09
Diluted net income per share	$ (0.10)	$ 3.39	$ (0.13)	$ (0.04)	$ (0.05)	$ 2.71	$ 0.23	$ (0.06)	$ 3.12	$ 2.83	$ 2.60