GOODWILL AND INTANGIBLE ASSETS - Narrative (Detail) (USD $)	3 Months Ended		6 Months Ended					12 Months Ended		6 Months Ended	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Mar. 31, 2014	Sep. 30, 2014 Trade name	Mar. 31, 2014 Trade name	Mar. 31, 2014 Developed Technology, Accanto Systems	Mar. 31, 2014 Developed technology	Sep. 30, 2014 Acquired software and core technology	Sep. 30, 2014 Acquired software and core technology Included as cost of product revenue	Sep. 30, 2013 Acquired software and core technology Included as cost of product revenue	Sep. 30, 2014 Acquired software and core technology Included as cost of product revenue	Sep. 30, 2013 Acquired software and core technology Included as cost of product revenue	Sep. 30, 2014 Other acquired intangible assets Included as operating expense	Sep. 30, 2013 Other acquired intangible assets Included as operating expense	Sep. 30, 2014 Other acquired intangible assets Included as operating expense	Sep. 30, 2013 Other acquired intangible assets Included as operating expense	Sep. 30, 2014 Customer relationships	Sep. 30, 2014 Unified Service Delivery	Mar. 31, 2014 Unified Service Delivery	Sep. 30, 2014 Test Optimization	Mar. 31, 2014 Test Optimization
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 201,457,000		$ 201,457,000		$ 203,446,000															$ 199,100,000	$ 201,000,000	$ 2,400,000	$ 2,400,000
Carrying value of intangible assets	54,465,000		54,465,000		58,513,000
Payments to acquire software rights			92,000	153,000				500,000	300,000
Weighted average useful life of acquired intangible assets			10 years 1 month 6 days					6 years 3 months 18 days	3 years	6 years 8 months 12 days									13 years 3 months 18 days
Indefinite-lived intangible assets						18,600,000	18,600,000
Amortization expenses	$ 856,000	$ 857,000	$ 1,718,000	$ 1,711,000							$ 923,000	$ 824,000	$ 1,900,000	$ 1,600,000	$ 856,000	$ 884,000	$ 1,700,000	$ 1,800,000