CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Apr. 30, 2016	Apr. 30, 2015
Current assets:
Cash and cash equivalents	$ 124,287	$ 143,410
Short-term investments	103,404	85,381
Accounts receivable, net of allowance for doubtful accounts of $262 at April 30, 2016 and $606 at April 30, 2015	56,045	33,607
Unbilled receivables and retentions	18,899	17,356
Inventories, net	37,486	39,414
Deferred income taxes	5,432	5,265
Prepaid expenses and other current assets	4,150	4,599
Total current assets	349,703	329,032
Long-term investments	33,859	46,769
Property and equipment, net	16,762	13,499
Deferred income taxes	9,319	7,426
Other assets	750	741
Total assets	410,393	397,467
Current liabilities:
Accounts payable	17,712	19,243
Wages and related accruals	13,973	13,395
Income taxes payable	943	692
Customer advances	2,544	4,235
Other current liabilities	11,173	9,170
Total current liabilities	46,345	46,735
Deferred rent	1,714	1,381
Capital lease obligations - net of current portion	449
Other non-current liabilities	184
Liability for uncertain tax positions	$ 441	$ 439
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—23,359,925 shares at April 30, 2016 and 23,314,640 at April 30, 2015	$ 2	$ 2
Additional paid-in capital	154,274	148,293
Accumulated other comprehensive loss	(201)	(1,358)
Retained earnings	207,185	201,975
Total stockholders' equity	361,260	348,912
Total liabilities and stockholders' equity	$ 410,393	$ 397,467