CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Treasury Stock
Beginning Balances, (in shares) at Apr. 30, 2019		238,337,000				36,377,000
Beginning Balances, Value at Apr. 30, 2019	$ 541,527	$ 2,383	$ 767,636	$ (20,416)	$ 499,386	$ (707,462)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(150,247)				(150,247)
Other comprehensive income (loss)	(2,320)			(2,320)
Stock-based compensation	6,557		6,557
Stock-based awards exercised or vested	$ 1,056		(13,789)		(2,786)	$ 17,631
Stock-based awards exercised or vested (in shares)	900,000					906,000
Acquisition of treasury shares (in shares)						(314,000)
Acquisition of treasury shares	$ (9,185)					$ (9,185)
Repurchase and retirement of common shares (in shares)		(1,593,000)
Repurchase and retirement of common shares	(44,072)	$ (16)	(955)		(43,101)
Cash dividends declared - $0.26 per share	(52,512)				(52,512)
Ending Balances, (in shares) at Jul. 31, 2019		236,744,000				35,785,000
Ending Balances, Value at Jul. 31, 2019	290,804	$ 2,367	759,449	(22,736)	250,740	$ (699,016)
Beginning Balances, (in shares) at Apr. 30, 2020		228,207,000				35,731,000
Beginning Balances, Value at Apr. 30, 2020	71,041	$ 2,282	775,387	(51,576)	42,965	$ (698,017)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	91,259				91,259
Other comprehensive income (loss)	17,539			17,539
Stock-based compensation	7,422		7,422
Stock-based awards exercised or vested	$ 973		(10,027)		(1,247)	$ 12,247
Stock-based awards exercised or vested (in shares)	600,000					627,000
Acquisition of treasury shares (in shares)						(204,000)
Acquisition of treasury shares	$ (2,913)					$ (2,913)
Cash dividends declared - $0.26 per share	(50,044)				(50,044)
Ending Balances, (in shares) at Jul. 31, 2020		228,207,000				35,308,000
Ending Balances, Value at Jul. 31, 2020	$ 135,277	$ 2,282	$ 772,782	$ (34,037)	$ 82,933	$ (688,683)