Quarterly Financial And Market Information (Summary Of Quarterly Financial And Market Information) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Quarterly Financial And Market Information [Line Items]
Net revenue	$ 1,123		$ 808		$ 695		$ 949		$ 1,209		$ 922		$ 711		$ 955		$ 3,575	$ 3,797	$ 4,143
Gross profit	900		291		282		755		900		493		266		750		2,228	2,409	2,545
Operating income (loss)	344		(292)		(252)		233		309		(39)		(364)		215		33	121	35
Net income (loss)	367	[1]	(308)	[2]	(273)	[3]	222	[4]	323	[5]	(45)	[6]	(381)	[7]	201	[8]	8	98	76
Net income (loss) per share - Basic	$ 1.18		$ (1.00)		$ (0.89)		$ 0.73		$ 1.07		$ (0.15)		$ (1.21)		$ 0.63		$ 0.03	$ 0.32	$ 0.23
Net income (loss) per share - Diluted	$ 1.15		$ (1.00)		$ (0.89)		$ 0.71		$ 1.05		$ (0.15)		$ (1.21)		$ 0.63		$ 0.03	$ 0.31	$ 0.23
High price, Common stock per share	$ 30.25		$ 26.44		$ 27.99		$ 23.61		$ 19.34		$ 15.42		$ 14.50		$ 16.71		$ 30.25	$ 19.34
Low price, Common stock per share	$ 21.54		$ 20.97		$ 23.18		$ 16.91		$ 13.70		$ 11.91		$ 10.94		$ 11.89		$ 16.91	$ 10.94
Acquisition-related contingent consideration			(1)		(44)		7		1		(45)				(20)		(35)	(64)	11
Impairment charges	1								31		6							39	12
Gains on strategic investments, net	2								(25)		(14)						0	39	0
Restructuring Charges					$ 2		$ (1)				$ (2)		$ 2		$ (27)		$ 1	$ (27)	$ (16)

[1] Net income includes restructuring charges of $1 million and $2 million of acquisition-related contingent consideration, both of which are pre-tax amounts.

[2] Net loss includes pre-tax restructuring charges of $(1) million.

[3] Net loss includes restructuring charges of $(2) million and $(44) million of acquisition-related contingent consideration, both of which are pre-tax amounts.

[4] Net income includes restructuring charges of $1 million and $7 million of acquisition-related contingent consideration, both of which are pre-tax amounts.

[5] Net income includes $31 million of impairment charges on acquisition-related intangible assets, $(25) million of gain on strategic investments, net, and $1 million of acquisition-related contingent consideration, both of which are pre-tax amounts.

[6] Net loss includes $(45) million of acquisition-related contingent consideration, $(14) million gain on strategic investments, net, $6 million of impairment charges on acquisition-related intangible assets, and restructuring charges of $2 million, all of which are pre-tax amounts.

[7] Net loss includes pre-tax restructuring charges of $(2) million.

[8] Net income includes restructuring charges of $27 million and $(20) million of acquisition-related contingent consideration, both of which are pre-tax amounts.