FAIR VALUE MEASUREMENTS - Schedule of Financial Assets and Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Mar. 31, 2013
ASSETS:
Cash and cash equivalents	$ 94,917	$ 99,930
Marketable securities	64,532	54,161
Derivative financial instruments	341	71
Total assets	159,790	154,162
LIABILITIES:
Contingent purchase consideration	(4,139)	(5,087)
Contingent contractual non-compliance liability	(148)	(246)
Derivative financial instruments	(221)	(249)
Total liabilities	(4,508)	(5,582)
U.S. government and municipal obligations
ASSETS:
Marketable securities	39,167	31,645
Commercial paper
ASSETS:
Marketable securities	5,597	12,390
Corporate bonds
ASSETS:
Marketable securities	17,109	5,166
Certificates of deposit
ASSETS:
Marketable securities	2,659	4,960
Level 1
ASSETS:
Cash and cash equivalents	94,917	99,930
Derivative financial instruments	0	0
Total assets	151,193	136,741
LIABILITIES:
Contingent purchase consideration	0	0
Contingent contractual non-compliance liability	0	0
Derivative financial instruments	0	0
Total liabilities	0	0
Level 1 | U.S. government and municipal obligations
ASSETS:
Marketable securities	39,167	31,645
Level 1 | Commercial paper
ASSETS:
Marketable securities	0	0
Level 1 | Corporate bonds
ASSETS:
Marketable securities	17,109	5,166
Level 1 | Certificates of deposit
ASSETS:
Marketable securities	0	0
Level 2
ASSETS:
Cash and cash equivalents	0	0
Derivative financial instruments		71
Total assets	8,597	17,421
LIABILITIES:
Contingent purchase consideration	0	0
Contingent contractual non-compliance liability	0	0
Derivative financial instruments	(221)	(249)
Total liabilities	(221)	(249)
Level 2 | U.S. government and municipal obligations
ASSETS:
Marketable securities	0	0
Level 2 | Commercial paper
ASSETS:
Marketable securities	5,597	12,390
Level 2 | Corporate bonds
ASSETS:
Marketable securities	0	0
Level 2 | Certificates of deposit
ASSETS:
Marketable securities	2,659	4,960
Level 3
ASSETS:
Cash and cash equivalents	0	0
Derivative financial instruments	0	0
Total assets	0	0
LIABILITIES:
Contingent purchase consideration	(4,139)	(5,087)
Contingent contractual non-compliance liability	(148)	(246)
Derivative financial instruments	0	0
Total liabilities	(4,287)	(5,333)
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
Level 3 | Certificates of deposit
ASSETS:
Marketable securities	$ 0	$ 0