CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Mar. 31, 2014
Current assets:
Cash and cash equivalents	$ 235,250	$ 232,704
Short-term investments	93,187	102,717
Accounts receivable, net	150,765	138,301
Inventory, net	60,968	57,132
Deferred tax assets	11,507	11,776
Other current assets	13,949	13,657
Total current assets	565,626	556,287
Long-term investments	108,784	100,342
Property, plant, and equipment, net	137,046	134,402
Goodwill and purchased intangibles, net	16,115	16,165
Other assets	2,149	4,619
Total assets	829,720	811,815
Current liabilities:
Accounts payable	36,751	30,756
Accrued liabilities	61,489	66,851
Total current liabilities	98,240	97,607
Long-term income taxes payable	13,195	12,719
Other long-term liabilities	4,556	2,825
Total liabilities	115,991	113,151
Commitments and contingencies (Note 5)
Stockholders' equity:
Common stock	776	770
Additional paid-in capital	673,545	663,483
Accumulated other comprehensive income	3,577	2,638
Retained earnings	145,672	123,389
Total stockholders' equity before treasury stock	823,570	790,280
Less: Treasury stock, at cost	(109,841)	(91,616)
Total stockholders' equity	713,729	698,664
Total liabilities and stockholders' equity	$ 829,720	$ 811,815