Consolidated Statements of Shareholders' Equity Consolidated Statements of Shareholders' Equity - 3 months ended Jul. 31, 2017 - USD ($) $ in Thousands	Total	Common stock	Retained earnings
Beginning Balance (shares) at Apr. 30, 2017		38,765,821,000
Beginning Balance at Apr. 30, 2017	$ 1,190,620	$ 40,074	$ 1,150,546
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	56,758		56,758
Dividends declared	(9,924)		(9,924)
Exercise of stock options (shares)		7,050,000
Exercise of stock options	$ 195	$ 195
Repurchase of common stock (shares)	(718,369,000)
Repurchase of common stock	$ (77,879)	$ (47,011)	(30,868)
Stock based compensation (shares)		56,393,000
Stock based compensation	6,742	$ 6,742
Ending Balance (shares) at Jul. 31, 2017		38,110,895,000
Ending Balance at Jul. 31, 2017	$ 1,166,512	$ 0	$ 1,166,512