FAIR VALUE MEASUREMENTS - Schedule of Financial Assets and Liabilities (Detail) (USD $)	Sep. 30, 2014	Mar. 31, 2014
ASSETS:
Cash and cash equivalents	$ 78,986,000	$ 102,076,000
Marketable securities	138,325,000	116,718,000
Derivative financial instruments	103,000	368,000
Total assets	217,414,000	219,162,000
LIABILITIES:
Contingent purchase consideration	(4,407,000)	(4,291,000)
Contingent contractual non-compliance liability		(49,000)
Derivative financial instruments	(735,000)	(139,000)
Total liabilities	(5,142,000)	(4,479,000)
U.S. government and municipal obligations
ASSETS:
Marketable securities	116,280,000	91,757,000
Commercial paper
ASSETS:
Marketable securities	15,987,000	14,581,000
Corporate bonds
ASSETS:
Marketable securities	6,058,000	10,380,000
Level 1
ASSETS:
Cash and cash equivalents	78,986,000	82,079,000
Derivative financial instruments	0	0
Total assets	125,931,000	114,451,000
LIABILITIES:
Contingent purchase consideration	0	0
Contingent contractual non-compliance liability		0
Derivative financial instruments	0	0
Total liabilities	0	0
Level 1 | U.S. government and municipal obligations
ASSETS:
Marketable securities	40,887,000	21,992,000
Level 1 | Commercial paper
ASSETS:
Marketable securities	0	0
Level 1 | Corporate bonds
ASSETS:
Marketable securities	6,058,000	10,380,000
Level 2
ASSETS:
Cash and cash equivalents	0	19,997,000
Derivative financial instruments	103,000	368,000
Total assets	91,483,000	104,711,000
LIABILITIES:
Contingent purchase consideration	0	0
Contingent contractual non-compliance liability		0
Derivative financial instruments	(735,000)	(139,000)
Total liabilities	(735,000)	(139,000)
Level 2 | U.S. government and municipal obligations
ASSETS:
Marketable securities	75,393,000	69,765,000
Level 2 | Commercial paper
ASSETS:
Marketable securities	15,987,000	14,581,000
Level 2 | Corporate bonds
ASSETS:
Marketable securities	0	0
Level 3
ASSETS:
Cash and cash equivalents	0	0
Derivative financial instruments	0	0
Total assets	0	0
LIABILITIES:
Contingent purchase consideration	(4,407,000)	(4,291,000)
Contingent contractual non-compliance liability	0	(49,000)
Derivative financial instruments	0	0
Total liabilities	(4,407,000)	(4,340,000)
Level 3 | U.S. government and municipal obligations
ASSETS:
Marketable securities	0	0
Level 3 | Commercial paper
ASSETS:
Marketable securities	0	0
Level 3 | Corporate bonds
ASSETS:
Marketable securities	$ 0	$ 0