Cash, Cash Equivalents and Investments with Hierarchy (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014
Amortized Costs	$ 149,327		$ 177,198
Gross Unrealized Gains	41		71
Gross Unrealized Loss	(221)		(175)
Estimated Fair Value	149,147		177,094
Cash and cash equivalents	28,795		53,110	$ 56,048		$ 59,159
Short-term marketable investments	120,352		123,984
Liabilities, Fair Value Disclosure	241	$ 241	0	$ 0	$ 0	$ 0
Aavailable-for-sale investments due within one year	63,313
Aavailable-for-sale investments due after one year	57,039
Level 1
Amortized Costs	30,795		55,110
Gross Unrealized Gains	0		0
Gross Unrealized Loss	(162)		(107)
Estimated Fair Value	30,633		55,003
Cash and cash equivalents	28,795		53,110
Short-term marketable investments	1,838		1,893
Level 2
Amortized Costs	118,532		122,088
Gross Unrealized Gains	41		71
Gross Unrealized Loss	(59)		(68)
Estimated Fair Value	118,514		122,091
Cash and cash equivalents	0		0
Short-term marketable investments	118,514		122,091
Level 3
Amortized Costs	0
Gross Unrealized Gains	0
Gross Unrealized Loss	0
Estimated Fair Value	241
Cash and cash equivalents	0
Short-term marketable investments	0
Liabilities, Fair Value Disclosure	241
Cash
Amortized Costs	4,435		24,734
Gross Unrealized Gains	0		0
Gross Unrealized Loss	0		0
Estimated Fair Value	4,435		24,734
Cash and cash equivalents	4,435		24,734
Short-term marketable investments	0		0
Money Market Funds | Level 1
Amortized Costs	24,360		28,376
Gross Unrealized Gains	0		0
Gross Unrealized Loss	0		0
Estimated Fair Value	24,360		28,376
Cash and cash equivalents	24,360		28,376
Short-term marketable investments	0		0
Mutual Funds | Level 1
Amortized Costs	2,000		2,000
Gross Unrealized Gains	0		0
Gross Unrealized Loss	(162)		(107)
Estimated Fair Value	1,838		1,893
Cash and cash equivalents	0		0
Short-term marketable investments	1,838		1,893
Commercial Paper | Level 2
Amortized Costs	8,787		9,043
Gross Unrealized Gains	1		1
Gross Unrealized Loss	0		0
Estimated Fair Value	8,788		9,044
Cash and cash equivalents	0		0
Short-term marketable investments	8,788		9,044
Corporate Debt | Level 2
Amortized Costs	68,702		75,284
Gross Unrealized Gains	24		57
Gross Unrealized Loss	(42)		(10)
Estimated Fair Value	68,684		75,331
Cash and cash equivalents	0		0
Short-term marketable investments	68,684		75,331
Municipal Securities | Level 2
Amortized Costs	7,762		5,435
Gross Unrealized Gains	3		2
Gross Unrealized Loss	(1)		(1)
Estimated Fair Value	7,764		5,436
Cash and cash equivalents	0		0
Short-term marketable investments	7,764		5,436
Asset-backed Securities | Level 2
Amortized Costs	21,881		21,503
Gross Unrealized Gains	7		4
Gross Unrealized Loss	(5)		(5)
Estimated Fair Value	21,883		21,502
Cash and cash equivalents	0		0
Short-term marketable investments	21,883		21,502
Mortgage backed Securities | Level 2
Amortized Costs	2,891		5,822
Gross Unrealized Gains	0		0
Gross Unrealized Loss	(9)		(52)
Estimated Fair Value	2,882		5,770
Cash and cash equivalents	0		0
Short-term marketable investments	2,882		5,770
Agency Bond | Level 2
Amortized Costs	7,508		4,201
Gross Unrealized Gains	5		3
Gross Unrealized Loss	(2)		0
Estimated Fair Value	7,511		4,204
Cash and cash equivalents	0		0
Short-term marketable investments	7,511		4,204
International Government Securities | Level 2
Amortized Costs	1,001		800
Gross Unrealized Gains	1		4
Gross Unrealized Loss	0		0
Estimated Fair Value	1,002		804
Cash and cash equivalents	0		0
Short-term marketable investments	1,002		$ 804
Contingent Consideration | Level 3
Amortized Costs	0
Gross Unrealized Gains	0
Gross Unrealized Loss	0
Estimated Fair Value	241
Cash and cash equivalents	0
Short-term marketable investments	0
Liabilities, Fair Value Disclosure	$ 241