Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Common Stock	Exchangeable Shares	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Total
Balance at Apr. 30, 2017	$ 410		$ 488,459	$ 26,621	$ (884)	$ 514,606
Balance (in shares) at Apr. 30, 2017	40,971
Increase (Decrease) in Stockholders' Equity
Net income				62,971		62,971
Change in other comprehensive income (loss), net of tax					1,325	1,325
Equity-based compensation			1,513			1,513
Tax withholding related to net share settlements of stock options/equity awards			(1,441)			(1,441)
Exercise of stock options	$ 1		476			477
Exercise of stock options (in shares)	98
Balance at Apr. 30, 2018	$ 411		489,007	89,592	441	579,451
Balance (in shares) at Apr. 30, 2018	41,069
Increase (Decrease) in Stockholders' Equity
Net income				56,002		56,002
Issuance of Exchangeable Shares		$ 29,639				29,639
Repurchase and retirement of common stock	$ (10)		(16,510)			(16,520)
Repurchase and retirement of common stock (in shares)	(978)
Foreign currency translation loss					(22,320)	(22,320)
Change in other comprehensive income (loss), net of tax					(4,695)	(4,695)
Equity-based compensation			3,726			3,726
Tax withholding related to net share settlements of stock options/equity awards			(50)			(50)
Exercise of stock options	$ 2		2,536			2,538
Exercise of stock options (in shares)	205
Vesting of restricted stock units (in shares)	5
Issuance of common stock pursuant to employee stock purchase plan	$ 1		1,404			1,405
Issuance of common stock pursuant to employee stock purchase plan (in shares)	74
Balance at Apr. 30, 2019	$ 404	29,639	480,113	145,594	(26,574)	$ 629,176
Balance (in shares) at Apr. 30, 2019	40,375					40,375
Increase (Decrease) in Stockholders' Equity
Net income				23,381		$ 23,381
Exercise of Exchangeable Shares	$ 11	$ (29,639)	29,628
Exercise of Exchangeable Shares (in shares)	1,129
Foreign currency translation loss					(18,257)	(18,257)
Change in other comprehensive income (loss), net of tax					(20,251)	(20,251)
Equity-based compensation			6,878			6,878
Tax withholding related to net share settlements of stock options/equity awards			(532)			(532)
Exercise of stock options	$ 9		11,784			11,793
Exercise of stock options (in shares)	857
Vesting of restricted stock units	$ 1		(1)
Vesting of restricted stock units (in shares)	78
Issuance of common stock pursuant to employee stock purchase plan	$ 1		1,792			1,793
Issuance of common stock pursuant to employee stock purchase plan (in shares)	115
Balance at Apr. 30, 2020	$ 426		$ 529,662	$ 168,975	$ (65,082)	$ 633,981
Balance (in shares) at Apr. 30, 2020	42,554					42,554