CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Mar. 31, 2012
Current assets:
Cash and cash equivalents	$ 207,929	$ 209,335
Short-term investments	152,500	125,177
Accounts receivable, net	108,070	111,771
Inventory, net	61,639	53,713
Deferred tax assets	11,218	11,090
Other current assets	13,131	13,088
Total current assets	554,487	524,174
Long-term investments	38,775	55,347
Property, plant and equipment, net	89,766	76,159
Goodwill and purchased intangibles, net	16,692	14,388
Other assets	2,694	2,402
Total assets	702,414	672,470
Current liabilities:
Accounts payable	30,435	34,126
Accrued liabilities	53,449	52,067
Total current liabilities	83,884	86,193
Deferred tax liabilities	2,494	8,673
Long-term income taxes payable	13,115	12,150
Revolving line of credit	29,000	37,000
Other long-term liabilities	1,141	1,210
Total liabilities	129,634	145,226
Commitments and contingencies (Note 7)
Stockholders' equity:
Common stock	749	741
Additional paid-in capital	582,104	557,218
Accumulated other comprehensive income	5,101	6,357
Retained earnings	156,355	115,358
Total stockholders' equity before treasury stock	744,309	679,674
Less: Treasury stock, at cost	(171,529)	(152,430)
Total stockholders' equity	572,780	527,244
Total liabilities and stockholders' equity	$ 702,414	$ 672,470