Consolidated Condensed Statements of Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Paid-In Capital	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Other Accumulated Comprehensive Income (Loss)	Other Accumulated Comprehensive Income (Loss) Cumulative Effect, Period of Adoption, Adjustment	Treasury Stock
Balance (shares) at May. 31, 2019			184,791						81,506
Balance at May. 31, 2019	$ 3,002,721	$ (833)	$ 840,328	$ 227,928	$ 6,691,236	$ (2,808)	$ (39,152)	$ 1,975	$ (4,717,619)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	250,812				250,812
Comprehensive loss, net of tax	(23,474)						(23,474)
Stock-based compensation	40,395			40,395
Vesting of stock-based compensation awards (shares)			605
Vesting of stock-based compensation awards	0		$ 157,882	(157,882)
Stock options exercised, net of shares surrendered (in shares)			557
Stock options exercised, net of shares surrendered	37,915		$ 37,915
Repurchase of common stock (shares)									(1,082)
Repurchase of common stock	(256,830)								$ (256,830)
Balance (shares) at Aug. 31, 2019			185,953						82,588
Balance at Aug. 31, 2019	3,050,706		$ 1,036,125	110,441	6,939,240		(60,651)		$ (4,974,449)
Balance (shares) at May. 31, 2020			186,793						83,378
Balance at May. 31, 2020	3,235,202		$ 1,102,689	171,521	7,296,509		(153,380)		$ (5,182,137)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	300,005				300,005
Comprehensive loss, net of tax	37,430						37,430
Stock-based compensation	29,055			29,055
Vesting of stock-based compensation awards (shares)			568
Vesting of stock-based compensation awards	0		$ 170,421	(170,421)
Stock options exercised, net of shares surrendered (in shares)			795
Stock options exercised, net of shares surrendered	72,123		$ 72,123
Repurchase of common stock (shares)									(230)
Repurchase of common stock	(69,011)								$ (69,011)
Balance (shares) at Aug. 31, 2020			188,156						83,608
Balance at Aug. 31, 2020	$ 3,604,804		$ 1,345,233	$ 30,155	$ 7,596,514		$ (115,950)		$ (5,251,148)