Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2020	Apr. 30, 2019	Apr. 30, 2018
Operating activities
Net income	$ 41,070	$ 47,419	$ 17,647
Loss (gain) on sale of business, net of tax	265	(8,490)
Loss from discontinued operations, net of tax		2,964	3,887
Net income from continuing operations	41,335	41,893	21,534
Adjustments to reconcile net income from continuing operations to cash provided by operating activities from continuing operations:
Depreciation and amortization	9,888	7,669	5,982
Losses from equity method investments	5,487	3,944	1,283
Realized gain from sale of available-for-sale investments	(180)
Impairment of long-lived assets		4,398	255
Provision for doubtful accounts	388	(39)	977
Impairment of intangible assets and goodwill			1,021
Other non-cash gain, net	(703)
Non-cash lease expense	4,574
Loss (gain) on foreign currency transactions	1	38	(87)
Deferred income taxes	3,419	4,792	2,853
Stock-based compensation	6,227	6,985	4,956
(Gain) loss on sale of property and equipment	(71)	76	20
Amortization of debt securities	(1,423)	(1,506)	1,424
Changes in operating assets and liabilities, net of acquisitions:
Accounts receivable	(42,869)	25,821	11,070
Unbilled receivables and retentions	(22,790)	(36,175)	2,253
Inventories	8,855	(16,631)	1,192
Income tax receivable	821	(821)
Prepaid expenses and other assets	831	(2,401)	139
Accounts payable	3,127	(7,054)	5,736
Other liabilities	8,180	(4,043)	9,224
Net cash provided by operating activities of continuing operations	25,097	26,946	69,832
Investing activities
Acquisition of property and equipment	(11,220)	(8,896)	(9,563)
Equity method investments	(14,498)	(7,598)	(3,267)
Business acquisition, net of cash acquired	(18,641)
Proceeds from sale of business		31,994
Proceeds from sale of property and equipment	81
Redemptions of held-to-maturity investments	185,917	260,918	227,663
Purchases of held-to-maturity investments	(176,757)	(267,122)	(221,680)
Redemptions of available-for-sale investments	200,892	2,250	450
Purchases of available-for-sale investments	(106,607)
Net cash provided by (used in) investing activities from continuing operations	59,167	11,546	(6,397)
Financing activities
Principal payments of capital lease obligations		(161)	(288)
Payment of contingent consideration	(868)
Tax withholding payment related to net settlement of equity awards	(1,062)	(1,094)	(397)
Exercise of stock options	100	71	2,705
Net cash used in financing activities from continuing operations	(1,830)	(1,184)	2,020
Discontinued operations
Operating activities of discontinued operations	0	(7,686)	(623)
Investing activities of discontinued operations	0	(431)	(1,219)
Net cash used in discontinued operations		(8,117)	(1,842)
Net increase in cash, cash equivalents, and restricted cash	82,434	29,191	63,613
Cash, cash equivalents, and restricted cash at beginning of period	172,708	143,517	79,904
Cash, cash equivalents, and restricted cash at end of period	255,142	172,708	143,517
Cash paid, net during the period for:
Income taxes	532	6,780	1,813
Non-cash activities
Unrealized gain on investments, net of deferred tax expense of $14, $51 and $25 for the fiscal years ended 2020, 2019 and 2018, respectively	50	57	70
Reclassification from share-based liability compensation to equity			384
Change in foreign currency translation adjustments	276	(34)	36
Acquisitions of property and equipment included in accounts payable	$ 1,425	$ 810	$ 379