Consolidated Statements of Shareholders' Equity Consolidated Statements of Shareholders' Equity - 9 months ended Jan. 31, 2018 - 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	298,641
Dividends declared	(29,467)		(29,467)
Exercise of stock options (shares)		24,535,000
Exercise of stock options	$ 801	$ 801
Repurchase of common stock (shares)	(1,321,854,000)
Repurchase of common stock	$ (144,104)	$ (51,901)	(92,203)
Stock based compensation (shares)		65,604,000
Stock based compensation	13,312	$ 13,312
Ending Balance (shares) at Jan. 31, 2018		37,534,106,000
Ending Balance at Jan. 31, 2018	$ 1,329,803	$ 2,286	$ 1,327,517