CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2018	Apr. 30, 2017	Apr. 30, 2016
Cash flows from operating activities:
Net income	$ 135,897	$ 87,238	$ 31,433
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	48,588	47,260	36,220
Stock-based compensation expense	21,469	18,958	18,895
Provision for doubtful accounts	13,675	12,987	8,570
Gain on cash surrender value of life insurance policies	(7,776)	(4,918)	(3,984)
(Gain) loss on marketable securities	(10,278)	(10,842)	3,333
Deferred income taxes	(6,564)	6,589	(13,792)
Change in other assets and liabilities, net of effect of acquisitions:
Deferred compensation	27,660	6,868	(4,605)
Receivables due from clients	(53,357)	(42,326)	(16,622)
Income taxes and other receivables	2,093	(10,177)	(191)
Prepaid expenses and other assets	(13,491)	(8,485)	(6,310)
Investment in unconsolidated subsidiaries	(297)	(333)	(1,631)
Income taxes payable	32,439	205	686
Accounts payable and accrued liabilities	66,081	5,420	18,862
Other	(37,014)	(2,303)	(1,875)
Net cash provided by operating activities	219,125	106,141	68,989
Cash flows from investing activities:
Purchase of property and equipment	(42,000)	(50,088)	(26,144)
Purchase of marketable securities	(9,462)	(10,536)	(30,397)
Proceeds from sales/maturities of marketable securities	2,642	42,815	30,066
Cash paid for acquisitions, net of cash acquired and earnout		(2,880)	(256,082)
Acquisition of Mexico subsidiary, net of cash acquired			3,973
Premiums on company-owned life insurance policies	(1,614)	(1,597)	(1,623)
Proceeds from life insurance policies	5,355	1,117	3,256
Dividends received from unconsolidated subsidiaries	240	564	2,373
Net cash used in investing activities	(44,839)	(20,605)	(274,578)
Cash flows from financing activities:
Proceeds from term loan facility		275,000	150,000
Principal payment on term loan facility	(20,625)	(155,469)	(10,000)
Payment of contingent consideration from acquisition	(485)	(1,070)
Repurchases of common stock	(33,071)	(28,821)
Payment of tax withholdings on restricted stock	(3,794)	(4,758)	(7,410)
Proceeds from issuance of common stock upon exercise of employee stock options and in connection with an employee stock purchase plan	6,885	5,121	4,038
Dividends - noncontrolling interest	(2,659)	(1,203)
Dividends paid to shareholders	(22,955)	(23,318)	(21,833)
Payments on life insurance policy loans	(554)	(1,117)	(1,251)
Net cash (used in) provided by financing activities	(77,258)	64,365	113,544
Effect of exchange rate changes on cash and cash equivalents	12,938	(12,271)	(15,541)
Net increase (decrease) in cash and cash equivalents	109,966	137,630	(107,586)
Cash and cash equivalents at beginning of year	410,882	273,252	380,838
Cash and cash equivalents at end of year	520,848	410,882	273,252
Supplemental cash flow information:
Cash used to pay interest	11,946	10,882	5,154
Cash used to pay income taxes, net of refunds	$ 37,486	$ 32,458	$ 33,189