CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Mar. 31, 2014
Current assets:
Cash and cash equivalents	$ 268,229	$ 232,704
Short-term investments	90,290	102,717
Accounts receivable, net	140,427	138,301
Inventory, net	63,551	57,132
Deferred tax assets	11,255	11,776
Other current assets	18,420	13,657
Total current assets	592,172	556,287
Long-term investments	111,720	100,342
Property, plant, and equipment, net	138,324	134,402
Goodwill and purchased intangibles, net	16,204	16,165
Other assets	2,929	4,619
Total assets	861,349	811,815
Current liabilities:
Accounts payable	38,914	30,756
Accrued liabilities	56,129	66,851
Total current liabilities	95,043	97,607
Long-term income taxes payable	13,776	12,719
Other long-term liabilities	5,010	2,825
Total liabilities	113,829	113,151
Commitments and contingencies (Note 5)
Stockholders' equity:
Common stock	779	770
Additional paid-in capital	689,301	663,483
Accumulated other comprehensive income	6,711	2,638
Retained earnings	166,646	123,389
Total stockholders' equity before treasury stock	863,437	790,280
Less: Treasury stock, at cost	(115,917)	(91,616)
Total stockholders' equity	747,520	698,664
Total liabilities and stockholders' equity	$ 861,349	$ 811,815