Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Jan. 27, 2018	Jan. 28, 2017
Operating activities
Net income (loss)	$ 1,509	$ (17,997)
Adjustments to reconcile net income (loss) to cash provided by (used in) operating activities:
Depreciation and amortization	5,605	5,188
Loss from equity method investments	418	119
Impairment of long-lived assets	255
Provision for doubtful accounts	1,102	115
Impairment of intangible assets and goodwill	1,021
(Gains) losses on foreign currency transactions	(36)	272
Deferred income taxes	175	(698)
Stock-based compensation	3,899	2,736
Tax benefit from exercise of stock options		22
Loss on disposition of property and equipment	15	37
Amortization of held-to-maturity investments	1,250	1,827
Changes in operating assets and liabilities:
Accounts receivable	47,652	32,553
Unbilled receivables and retentions	(10,841)	4,079
Inventories	(17,251)	(31,320)
Income tax receivable	(292)	(2,487)
Prepaid expenses and other assets	472	(1,190)
Accounts payable	(6,684)	(3,170)
Other liabilities	(153)	(4,510)
Net cash provided by (used in) operating activities	28,116	(14,424)
Investing activities
Acquisition of property and equipment	(8,450)	(7,586)
Equity method investments	(1,860)
Redemptions of held-to-maturity investments	163,813	93,208
Purchases of held-to-maturity investments	(151,740)	(122,978)
Proceeds from the sale of property and equipment		7
Redemptions of available-for-sale investments	450	400
Net cash provided by (used in) investing activities	2,213	(36,949)
Financing activities
Principal payments of capital lease obligations	(231)	(291)
Tax withholding payment related to net settlement of equity awards	(389)
Exercise of stock options	2,691	655
Net cash provided by financing activities	2,071	364
Net increase (decrease) in cash and cash equivalents	32,400	(51,009)
Cash and cash equivalents at beginning of period	79,904	124,287
Cash and cash equivalents at end of period	112,304	73,278
Cash paid, net during the period for:
Income taxes	1,812	1,786
Non-cash activities
Unrealized gain on investments, net of deferred tax expense of $29 and $6, respectively	42	32
Reclassification from share-based liability compensation to equity	384	307
Change in foreign currency translation adjustments	62
Acquisitions of property and equipment included in accounts payable	$ 332	$ 408