Effect of Foreign Exchange Forward Contracts on Other Comprehensive Income And Results Of Operations (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2012		Dec. 31, 2011
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative	$ (46)	[1]	$ 359	[1]	$ (22)	[1]	$ 665	[1]
Gain (Loss) Reclassified from Accumulated OCI into Income	15	[2]	252	[2]	(248)	[2]	31	[2]
Gain (Loss) Recognized in Income (Amount Excluded from Effectiveness Testing)	42	[3]	(22)	[3]	133	[3]	(133)	[3]
Forward Contracts | Research And Development
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative	(46)	[1]	359	[1]	(22)	[1]	665	[1]
Gain (Loss) Reclassified from Accumulated OCI into Income	(52)	[2]	136	[2]	(289)	[2]	138	[2]
Gain (Loss) Recognized in Income (Amount Excluded from Effectiveness Testing)	51	[3]	(15)	[3]	137	[3]	(91)	[3]
Forward Contracts | Sales And Marketing
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Reclassified from Accumulated OCI into Income	67	[2]	116	[2]	41	[2]	(107)	[2]
Gain (Loss) Recognized in Income (Amount Excluded from Effectiveness Testing)	$ (9)	[3]	$ (7)	[3]	$ (4)	[3]	$ (42)	[3]

[1] The amount represents the change in fair value of derivative contracts due to changes in spot rates.

[2] The amount represents reclassification from other comprehensive income to earnings that occurs when the hedged item affects earnings.

[3] The amount represents the change in fair value of derivative contracts due to changes in the difference between the spot price and forward price that is excluded from the assessment of hedge effectiveness and therefore recognized in earnings. No gains or losses were reclassified as a result of discontinuance of cash flow hedges.