Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2010
Operating activities:
Net loss	$ (82,688)	$ (1,006)	$ (7,485)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Depreciation	8,436	7,243	6,778
Amortization of purchased intangibles	6,754	17,167	16,117
Stock-based compensation expense:
Stock options	5,298	5,592	4,125
Restricted stock units	13,076	11,092	9,557
Veloce accrued liability	60,400
Non-cash restructuring charges			359
Acquisition related adjustment	(2,532)
Capitalization of mask set cost		(1,177)
(Gain) impairment on strategic investment, net	(7,147)		2,000
Impairment of short term investments and marketable securities			4,287
Tax benefit from other comprehensive income	(123)		(6,204)
Net gain (loss) on disposals of property	10	(322)	145
Net gain on sale of storage business unit			(11,366)
Changes in operating assets and liabilities, net of amounts acquired:
Accounts receivable	(2,669)	3,465	(5,355)
Inventories	3,317	(11,174)	10,754
Other assets	(3,903)	(1,561)	(237)
Accounts payable	(4,451)	1,842	2,245
Accrued payroll and other accrued liabilities	(2,860)	(1,162)	(7,077)
Deferred revenue	(270)	956	(1,776)
Net cash (used in) provided by operating activities	(9,352)	30,955	16,867
Investing activities:
Proceeds from sales and maturities of short-term investments	101,222	121,876	185,724
Purchases of short-term investments	(103,046)	(124,950)	(173,265)
Purchase of property, equipment and other assets	(13,264)	(9,740)	(7,532)
Proceeds from the sale of strategic investment		4,991
Purchase of strategic investment/s	(4,750)	(330)	(1,000)
Proceeds from sale of storage business unit			21,527
Proceeds from sale of property and equipment		365
Purchase of a business, net of cash acquired		(31,484)
Net cash (used for) provided by investing activities	(19,838)	(39,272)	25,454
Financing activities:
Proceeds from issuance of common stock	6,736	8,045	3,825
Funding of restricted stock units withheld for taxes	(2,864)	(2,746)	(870)
Repurchase of common stock	(20,852)	(40,063)	(8,076)
Funding of structured stock repurchase agreements	(10,000)	(10,000)	(41,797)
Funds received from structured stock repurchase agreements, including gains		15,512	27,751
Other	(167)	(555)	35
Net cash used for financing activities	(27,147)	(29,807)	(19,132)
Net (decrease) increase in cash and cash equivalents	(56,337)	(38,124)	23,189
Cash and cash equivalents at beginning of year	84,402	122,526	99,337
Cash and cash equivalents at end of year	28,065	84,402	122,526
Supplementary cash flow disclosure:
Cash paid for Income taxes	$ 692	$ 327	$ 48