CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Apr. 30, 2014	Apr. 30, 2013
Current assets:
Cash and cash equivalents	$ 126,969	$ 75,332
Short-term investments	70,639	73,241
Accounts receivable, net of allowance for doubtful accounts of $791 at April 30, 2014 and $936 at April 30, 2013	31,739	19,770
Unbilled receivables and retentions	10,929	11,304
Inventories, net	50,699	62,561
Income tax receivable	6,584	11,777
Deferred income taxes	5,038	5,166
Prepaid expenses and other current assets	4,260	4,303
Total current assets	306,857	263,454
Long-term investments	50,505	68,916
Property and equipment, net	19,997	24,429
Deferred income taxes	6,721	3,745
Other assets	874	1,060
Total assets	384,954	361,604
Current liabilities:
Accounts payable	13,906	16,144
Wages and related accruals	14,083	12,116
Customer advances	2,984	7,519
Other current liabilities	6,762	6,408
Total current liabilities	37,735	42,187
Deferred rent	1,239	771
Liability for uncertain tax positions	3,513	3,460
Commitments and contingencies
Stockholders' equity:
Preferred stock, $0.0001 par value: Authorized shares-10,000,000; none issued or outstanding
Common stock, $0.0001 par value: Authorized shares-100,000,000 Issued and outstanding shares-23,176,576 shares at April 30, 2014 and 22,614,315 at April 30, 2013	2	2
Additional paid-in capital	143,648	130,527
Accumulated other comprehensive loss	(263)	(705)
Retained earnings	199,080	185,362
Total stockholders' equity	342,467	315,186
Total liabilities and stockholders' equity	$ 384,954	$ 361,604