Basis of Presentation, Business and Summary of Significant Accounting Policies - Revision of Previously Issued Statements of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2015
Cash flows from investing activities:
Acquisition of businesses, net of cash acquired	$ (150,428)	$ (120,195)	$ (67,696)
Cash used in investing activities	(157,516)	(118,040)	(82,467)
Cash flows from financing activities:
Cash provided by financing activities	$ 86,297	77,081	14,066
As previously reported
Cash flows from investing activities:
Acquisition of businesses, net of cash acquired		(113,597)	(66,695)
Cash used in investing activities		(111,442)	(81,466)
Cash flows from financing activities:
Cash paid for contingent consideration		(6,598)	(1,001)
Cash provided by financing activities		70,483	13,065
Correction for misstatement of cash flows related to payments of working capital settlements \| Adjustment
Cash flows from investing activities:
Acquisition of businesses, net of cash acquired		(6,598)	(1,001)
Cash used in investing activities		(6,598)	(1,001)
Cash flows from financing activities:
Cash paid for contingent consideration		6,598	1,001
Cash provided by financing activities		$ 6,598	$ 1,001

Amount of cash outflow, not made soon after acquisition date of business combination, to settle contingent consideration liability up to amount recognized at acquisition date, including, but not limited to, measurement period adjustment and less amount paid soon after acquisition date.

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Amount of cash inflow (outflow) of financing activities, excluding discontinued operations. Financing activity cash flows include obtaining resources from owners and providing them with a return on, and a return of, their investment; borrowing money and repaying amounts borrowed, or settling the obligation; and obtaining and paying for other resources obtained from creditors on long-term credit.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 26
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3574-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 24
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3521-108585

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- Definition

Amount of cash inflow (outflow) of investing activities, excluding discontinued operations. Investing activity cash flows include making and collecting loans and acquiring and disposing of debt or equity instruments and property, plant, and equipment and other productive assets.

+ References

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- Definition

The cash outflow associated with the acquisition of a business, net of the cash acquired from the purchase.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3213-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Investing Activities
-URI http://asc.fasb.org/extlink&oid=6516133

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