Quarterly Financial Information (unaudited) - Operating Results (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended											12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015		Dec. 31, 2014	Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Schedule of Quarterly Information [Line Items]
Net revenues	$ 41,108	$ 40,623	$ 39,743	$ 37,813	$ 37,047	[1]	$ 36,747	$ 40,945	[2]	$ 50,272	[3]	$ 159,287	$ 165,011	$ 216,150
Cost of revenues	16,934	18,241	17,758	16,806	16,482	[1]	14,842	17,716	[2]	20,257	[3]	69,739	69,297	85,189
Gross profit	24,174	22,382	21,985	21,007	20,565	[1]	21,905	23,229	[2]	30,015	[3]	89,548	95,714	130,961
Total operating expenses	33,194	30,580	30,799	30,477	36,641	[1]	33,649	32,562	[2]	43,536	[3]	125,050	146,388	141,442
Operating loss	(9,020)	(8,198)	(8,814)	(9,470)	(16,076)	[1]	(11,744)	(9,333)	[2]	(13,521)	[3]	(35,502)	(50,674)	(10,481)
Interest and other income (expense)	229	169	265	1,644	1,030	[1]	475	(2,112)	[2]	315	[3]	2,238	2,764	5,052
Loss before income taxes	(8,791)	(8,029)	(8,549)	(7,826)	(15,046)	[1]	(11,269)	(11,445)	[2]	(13,206)	[3]	(33,195)	(50,966)	(5,075)
Income tax (benefit) expense	116	170	(488)	(422)	99	[1]	862	272	[2]	(141)	[3]	(624)	1,092	619
Net loss	$ (8,907)	$ (8,199)	$ (8,061)	$ (7,404)	$ (15,145)	[1]	$ (12,131)	$ (11,717)	[2]	$ (13,065)	[3]	(32,571)	(52,058)	(5,694)
Basic net income (loss) per share (in shares)	$ (0.11)	$ (0.10)	$ (0.10)	$ (0.09)	$ (0.19)	[1]	$ (0.15)	$ (0.15)	[2]	$ (0.17)	[3]
Shares used in calculating basic net income (loss) per share (shares)	84,127	83,191	82,176	81,179	80,667	[1]	78,920	78,487	[2]	77,916	[3]
Restructuring charges					$ (4,100)					$ (1,200)		$ (25)	$ (5,421)	$ (1,134)
Other-than-temporary impairment charges					500			$ 2,500
Veloce Technologies Inc.
Schedule of Quarterly Information [Line Items]
Research and development expenses incurred					$ 2,100					$ 7,100

[1] The consolidated operating results for the fourth quarter of fiscal 2015 included a charge of $2.1 million related to the Veloce consideration, a charge of $4.1 million related to restructuring and an impairment charge of $0.5 million related to a strategic investment.

[2] The consolidated operating results for the second quarter of fiscal 2015 included an impairment charge of $2.5 million related to a strategic investment.

[3] The consolidated operating results for the first quarter of fiscal 2015 included a charge of $7.1 million related to the Veloce consideration and a charge of $1.2 million related to restructuring.