FAIR VALUE MEASUREMENTS (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Sep. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Mar. 31, 2015
Amortized Costs	$ 172,868		$ 163,005
Gross Unrealized Gains	69		89
Gross Unrealized Loss	(286)		(244)
Estimated Fair Value	172,651		162,850
Cash and cash equivalents	33,457		33,576
Short-term marketable investments	139,194		129,274
Liabilities, Fair Value Disclosure	148	$ 216	341	$ 341	$ 391	$ 0
Aavailable-for-sale investments due within one year	86,842
Aavailable-for-sale investments due after one year	52,352
Level 1
Amortized Costs	35,457		35,576
Gross Unrealized Gains	0		0
Gross Unrealized Loss	(202)		(187)
Estimated Fair Value	35,255		35,389
Cash and cash equivalents	33,457		33,576
Short-term marketable investments	1,798		1,813
Level 2
Amortized Costs	137,411		127,429
Gross Unrealized Gains	69		89
Gross Unrealized Loss	(84)		(57)
Estimated Fair Value	137,396		127,461
Cash and cash equivalents	0		0
Short-term marketable investments	137,396		127,461
Level 3
Amortized Costs	0		0
Gross Unrealized Gains	0		0
Gross Unrealized Loss	0		0
Estimated Fair Value	148		148
Cash and cash equivalents	0		0
Short-term marketable investments	0		0
Liabilities, Fair Value Disclosure	148		148
Cash
Amortized Costs	27,382		18,596
Gross Unrealized Gains	0		0
Gross Unrealized Loss	0		0
Estimated Fair Value	27,382		18,596
Cash and cash equivalents	27,382		18,596
Short-term marketable investments	0		0
Money Market Funds | Level 1
Amortized Costs	6,075		14,980
Gross Unrealized Gains	0		0
Gross Unrealized Loss	0		0
Estimated Fair Value	6,075		14,980
Cash and cash equivalents	6,075		14,980
Short-term marketable investments	0		0
Mutual Funds | Level 1
Amortized Costs	2,000		2,000
Gross Unrealized Gains	0		0
Gross Unrealized Loss	(202)		(187)
Estimated Fair Value	1,798		1,813
Cash and cash equivalents	0		0
Short-term marketable investments	1,798		1,813
Commercial Paper | Level 2
Amortized Costs	20,945		6,794
Gross Unrealized Gains	4		2
Gross Unrealized Loss	(2)		0
Estimated Fair Value	20,947		6,796
Cash and cash equivalents	0		0
Short-term marketable investments	20,947		6,796
Corporate Debt | Level 2
Amortized Costs	90,469		85,164
Gross Unrealized Gains	57		78
Gross Unrealized Loss	(65)		(28)
Estimated Fair Value	90,461		85,214
Cash and cash equivalents	0		0
Short-term marketable investments	90,461		85,214
Municipal Securities | Level 2
Amortized Costs			1,007
Gross Unrealized Gains			0
Gross Unrealized Loss			(1)
Estimated Fair Value			1,006
Cash and cash equivalents			0
Short-term marketable investments			1,006
Asset-backed Securities | Level 2
Amortized Costs	22,630		24,614
Gross Unrealized Gains	7		7
Gross Unrealized Loss	(15)		(11)
Estimated Fair Value	22,622		24,610
Cash and cash equivalents	0		0
Short-term marketable investments	22,622		24,610
Mortgage backed Securities | Level 2
Amortized Costs	367		2,045
Gross Unrealized Gains	0		0
Gross Unrealized Loss	(2)		(17)
Estimated Fair Value	365		2,028
Cash and cash equivalents	0		0
Short-term marketable investments	365		2,028
Agency Bond | Level 2
Amortized Costs	2,000		6,805
Gross Unrealized Gains	1		1
Gross Unrealized Loss	0		0
Estimated Fair Value	2,001		6,806
Cash and cash equivalents	0		0
Short-term marketable investments	2,001		6,806
International Government Securities | Level 2
Amortized Costs	1,000		1,000
Gross Unrealized Gains	0		1
Gross Unrealized Loss	0		0
Estimated Fair Value	1,000		1,001
Cash and cash equivalents	0		0
Short-term marketable investments	1,000		1,001
Contingent Consideration | Level 3
Amortized Costs	0		0
Gross Unrealized Gains	0		0
Gross Unrealized Loss	0		0
Estimated Fair Value	148		148
Cash and cash equivalents	0		0
Short-term marketable investments	0		0
Liabilities, Fair Value Disclosure	$ 148		$ 148