CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Mar. 31, 2013
Current assets:
Cash and cash equivalents	$ 235,534	$ 228,776
Short-term investments	86,397	116,581
Accounts receivable, net	133,379	128,209
Inventory, net	66,569	67,435
Deferred tax assets	14,351	10,120
Other current assets	16,875	15,369
Total current assets	553,105	566,490
Long-term investments	106,800	80,261
Property, plant, and equipment, net	124,933	99,111
Goodwill and purchased intangibles, net	16,215	16,440
Other assets	2,317	2,303
Total assets	803,370	764,605
Current liabilities:
Accounts payable	26,728	37,067
Accrued liabilities	66,615	66,419
Total current liabilities	93,343	103,486
Deferred tax liabilities	2,024	1,742
Long-term income taxes payable	13,460	12,005
Other long-term liabilities	2,295	925
Total liabilities	111,122	118,158
Commitments and contingencies (Note 7)
Stockholders' equity:
Common stock	768	757
Additional paid-in capital	652,503	612,283
Accumulated other comprehensive income	1,773	5,567
Retained earnings	99,713	28,344
Total stockholders' equity before treasury stock	754,757	646,951
Less: Treasury stock, at cost	(62,509)	(504)
Total stockholders' equity	692,248	646,447
Total liabilities and stockholders' equity	$ 803,370	$ 764,605