Quarterly Financial Information (unaudited) - Operating Results (Details) (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	3 Months Ended													9 Months Ended	12 Months Ended			0 Months Ended	3 Months Ended						9 Months Ended		12 Months Ended			21 Months Ended
	Mar. 31, 2014	Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012		Sep. 30, 2012	Jun. 30, 2012	Dec. 31, 2012	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012	Apr. 22, 2013 TPack	Jun. 30, 2013 TPack	Dec. 31, 2013 Veloce Technologies Inc.	Sep. 30, 2013 Veloce Technologies Inc.	Jun. 30, 2013 Veloce Technologies Inc.	Mar. 31, 2013 Veloce Technologies Inc.	Mar. 31, 2012 Veloce Technologies Inc.	Mar. 31, 2013 Veloce Technologies Inc.	Dec. 31, 2012 Veloce Technologies Inc.	Mar. 31, 2014 Veloce Technologies Inc.	Mar. 31, 2013 Veloce Technologies Inc.	Mar. 31, 2012 Veloce Technologies Inc.	Mar. 31, 2014 Veloce Technologies Inc.
Schedule of Quarterly Information [Line Items]
Net revenues	$ 51,771,000	$ 54,844,000	[1]	$ 55,387,000	[2]	$ 54,148,000	[3]	$ 56,326,000	[4],[5]	$ 51,698,000	[6]	$ 46,324,000	$ 41,294,000		$ 216,150,000	$ 195,642,000	$ 230,887,000
Cost of revenues	19,806,000	21,644,000	[1]	21,397,000	[2]	22,342,000	[3]	21,174,000	[4],[5]	22,958,000	[6]	20,561,000	18,355,000		85,189,000	83,048,000	98,804,000
Gross profit	31,965,000	33,200,000	[1]	33,990,000	[2]	31,806,000	[3]	35,152,000	[4],[5]	28,740,000	[6]	25,763,000	22,939,000		130,961,000	112,594,000	132,083,000
Total operating expenses	9,229,000	40,900,000	[1]	66,757,000	[2]	24,556,000	[3]	49,116,000	[4],[5]	101,942,000	[6]	48,515,000	47,891,000		141,442,000	247,464,000	225,527,000
Operating loss	22,736,000	(7,700,000)	[1]	(32,767,000)	[2]	7,250,000	[3]	(13,964,000)	[4],[5]	(73,202,000)	[6]	(22,752,000)	(24,952,000)		(10,481,000)	(134,870,000)	(93,444,000)
Interest and other income (expense)	418,000	617,000	[1]	576,000	[2]	3,795,000	[3]	(4,654,000)	[4],[5]	2,258,000	[6]	835,000	1,762,000		5,052,000	2,595,000	4,247,000
Loss before income taxes	23,154,000	(7,083,000)	[1]	(32,191,000)	[2]	11,045,000	[3]	(18,618,000)	[4],[5]	(70,944,000)	[6]	(21,917,000)	(23,190,000)		(5,075,000)	(134,669,000)	(81,760,000)
Income tax expense	38,000	201,000	[1]	192,000	[2]	188,000	[3]	(1,012,000)	[4],[5]	618,000	[6]	(360,000)	200,000		619,000	(554,000)	928,000
Net loss	23,116,000	(7,284,000)	[1]	(32,383,000)	[2]	10,857,000	[3]	(17,606,000)	[4],[5]	(71,562,000)	[6]	(21,557,000)	(23,390,000)		(5,694,000)	(134,115,000)	(82,688,000)
Basic net income (loss) per share (in shares)	$ 0.31	$ (0.10)	[1]	$ (0.45)	[2]	$ 0.16	[3]	$ (0.26)	[4],[5]	$ (1.08)	[6]	$ (0.33)	$ (0.37)
Shares used in calculating basic net income (loss) per share (shares)	75,629	73,989	[1]	72,610	[2]	69,360	[3]	67,566	[4],[5]	66,113	[6]	64,947	62,409		72,897	65,258	62,245
Diluted net income (loss) per share (in shares)	$ 0.30	$ (0.10)	[1]	$ (0.45)	[2]	$ 0.15	[3]	$ (0.26)	[4],[5]	$ (1.08)	[6]	$ (0.33)	$ (0.37)
Shares used in calculating diluted income (loss) per share (shares)	77,193	73,989	[1]	72,610	[2]	70,234	[3]	67,566	[4],[5]	66,113	[6]	64,947	62,409		72,897	65,258	62,245
Research and development expenses incurred																				2,900,000	30,400,000	9,300,000	9,600,000	60,400,000	126,600,000	51,900,000	42,700,000	66,200,000		169,300,000
Gain on sale of TPack															19,699,000	0	0	19,699,000	19,700,000
Restructuring charges														(6,200,000)	(1,134,000)	(6,435,000)	(875,000)
Immaterial R&D expense error																							$ 10,400,000						$ 8,000,000

[1] The consolidated operating results for the third quarter of fiscal 2014 included a charge of $2.9 million related to the Veloce consideration.

[2] The consolidated operating results for the second quarter of fiscal 2014 included a charge of $30.4 million related to the Veloce consideration.

[3] The consolidated operating results for the first quarter of fiscal 2014 included a charge of $9.3 million related to the Veloce consideration and a gain on sale of TPack of $19.7 million.

[4] The consolidated operating results for the fourth quarter of fiscal 2013 included a charge of $9.6 million related to the Veloce consideration.

[5] During fiscal 2012, one significant product development milestone relating to the Veloce project was considered probable of achievement and accordingly $60.4 million was recognized as research and development expense (see further discussion in Note 4, Veloce, to the Consolidated Financial Statements). However, approximately $8.0 million of the R&D expense was incorrectly recognized as this expense amount related to Unallocated Veloce Units that had not yet been distributed as of March 31, 2012. R&D expenses were also recognized during the first three quarters of fiscal 2013 in connection with further progress made in connection with the performance milestones relating to Veloce. However, the R&D expenses recognized during the first three quarters of fiscal 2013 also incorrectly included immaterial amounts related to the Unallocated Veloce Units. During the fourth quarter of fiscal 2013, the Company corrected the error impacting fiscal 2012 and the first three quarters of fiscal 2013. The correction of the errors resulted in a reduction of R&D expenses recognized by $10.4 million during the fourth quarter of fiscal 2013.

[6] During the fiscal years ended March 31, 2014, 2013 and 2012, the Company recognized an impairment charge of its non-marketable strategic investment of $0.0 million, $2.3 million and $1.0 million, respectively. Refer to Note 1, Summary of Significant Accounting Policies, to the Consolidated Financial Statements for details.