Consolidated Statements of Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Cumulative effect of change in accounting principle	Common Stock	Paid-In Capital	Retained Earnings	Retained Earnings Cumulative effect of change in accounting principle	Other Accumulated Comprehensive Income (Loss)	Other Accumulated Comprehensive Income (Loss) Cumulative effect of change in accounting principle	Treasury Stock
Balance (shares) at May. 31, 2018			182,723						76,397
Beginning Balance at May. 31, 2018	$ 3,016,526	$ 189,192	$ 618,464	$ 245,211	$ 5,837,827	$ 189,192	$ 16,343		$ (3,701,319)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	884,981				884,981
Comprehensive income (loss), net of tax	(55,495)						(55,495)
Dividends	(220,764)				(220,764)
Stock-based compensation	139,210			139,210
Vesting of stock-based compensation awards (shares)			766
Vesting of stock-based compensation awards	0		$ 156,493	(156,493)
Stock options exercised, net of shares surrendered (in shares)			1,302
Stock options exercised, net of shares surrendered	65,371		$ 65,371
Repurchase of common stock (shares)									(5,109)
Repurchase of common stock	(1,016,300)								$ (1,016,300)
Balance (shares) at May. 31, 2019			184,791						81,506
Ending 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	876,037				876,037
Comprehensive income (loss), net of tax	(116,203)						(116,203)
Dividends	(267,956)				(267,956)
Stock-based compensation	115,435			115,435
Vesting of stock-based compensation awards (shares)			641
Vesting of stock-based compensation awards	0		$ 171,842	(171,842)
Stock options exercised, net of shares surrendered (in shares)			1,361
Stock options exercised, net of shares surrendered	90,519		$ 90,519
Repurchase of common stock (shares)									(1,872)
Repurchase of common stock	(464,518)								$ (464,518)
Balance (shares) at May. 31, 2020			186,793						83,378
Ending 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	1,110,968				1,110,968
Comprehensive income (loss), net of tax	184,268						184,268
Dividends	(530,462)				(530,462)
Stock-based compensation	112,035			112,035
Vesting of stock-based compensation awards (shares)			610
Vesting of stock-based compensation awards	0		$ 184,697	(184,697)
Stock options exercised, net of shares surrendered (in shares)			1,668
Stock options exercised, net of shares surrendered	129,957		$ 129,957
Repurchase of common stock (shares)									(1,632)
Repurchase of common stock	(554,121)								$ (554,121)
Balance (shares) at May. 31, 2021			189,071						85,010
Ending Balance at May. 31, 2021	$ 3,687,847		$ 1,417,343	$ 98,859	$ 7,877,015		$ 30,888		$ (5,736,258)