Changes in Accumulated Other Comprehensive Income by Component (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014		Sep. 30, 2013
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 61	$ 56	$ 37	[1]	$ 69
Other comprehensive income (loss) before reclassifications	(10)	6	9		(9)
Amounts reclassified from accumulated other comprehensive income	2	0	7		2
Net current-period other comprehensive income (loss)	(8)	6	16		(7)
Ending balance	53	62	53		62
Unrealized Gains (Losses) on Available-for-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(4)	(5)	(4)		(4)
Other comprehensive income (loss) before reclassifications	0	1	0		0
Amounts reclassified from accumulated other comprehensive income	0	0	0		0
Net current-period other comprehensive income (loss)	0	1	0		0
Ending balance	(4)	(4)	(4)		(4)
Unrealized Gains (Losses) on Derivative Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(6)	0	(10)		0
Other comprehensive income (loss) before reclassifications	11	(9)	10		(11)
Amounts reclassified from accumulated other comprehensive income	2	0	7		2
Net current-period other comprehensive income (loss)	13	(9)	17		(9)
Ending balance	7	(9)	7		(9)
Foreign Currency Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	71	61	51		73
Other comprehensive income (loss) before reclassifications	(21)	14	(1)		2
Amounts reclassified from accumulated other comprehensive income	0	0	0		0
Net current-period other comprehensive income (loss)	(21)	14	(1)		2
Ending balance	50	75	50		75
Sales Revenue, Net [Member] | Unrealized Gains (Losses) on Derivative Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Amounts reclassified from accumulated other comprehensive income	2		5
Research And Development [Member] | Unrealized Gains (Losses) on Derivative Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Amounts reclassified from accumulated other comprehensive income	$ 0		$ 2

[1] Derived from audited consolidated financial statements.