Consolidated Statements of Shareholders' Equity Statement - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Stockholders' Equity, Total [Member]
BALANCE, SHARES at Feb. 28, 2018		179,748,000
BALANCE at Feb. 28, 2018	$ 3,316,849	$ 89,874	$ 1,234,047	$ 2,047,240	$ (54,312)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	238,656			238,656
Other Comprehensive Income (Loss), Net of Tax	(733)				(733)
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	16,645		16,645
Stock Repurchased and Retired During Period, Shares		(3,308,000)
Stock Repurchased and Retired During Period, Value	(207,404)	$ (1,654)	(22,824)	(182,926)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period		212,000
Stock Issued During Period, Value, Stock Options Exercised	9,052	$ 106	8,946
Shares Issued, Shares, Share-based Payment Arrangement, after Forfeiture		68,000
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	(2,168)	$ 34	(2,202)
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification				12,864		$ 12,864
BALANCE, SHARES at May. 31, 2018		176,720,000
BALANCE at May. 31, 2018	3,383,761	$ 88,360	1,234,612	2,115,834	(55,045)
BALANCE, SHARES at Feb. 28, 2018		179,748,000
BALANCE at Feb. 28, 2018	3,316,849	$ 89,874	1,234,047	2,047,240	(54,312)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	649,857
Other Comprehensive Income (Loss), Net of Tax	175
BALANCE, SHARES at Nov. 30, 2018		171,785,000
BALANCE at Nov. 30, 2018	3,435,113	$ 85,893	1,255,966	2,147,391	(54,137)
BALANCE, SHARES at May. 31, 2018		176,720,000
BALANCE at May. 31, 2018	3,383,761	$ 88,360	1,234,612	2,115,834	(55,045)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	220,890			220,890
Other Comprehensive Income (Loss), Net of Tax	610				610
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	9,695		9,695
Stock Repurchased and Retired During Period, Shares		(2,291,000)
Stock Repurchased and Retired During Period, Value	(171,226)	$ (1,146)	(16,334)	(153,746)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period		860,000
Stock Issued During Period, Value, Stock Options Exercised	38,449	$ 430	38,019
Shares Issued, Shares, Share-based Payment Arrangement, after Forfeiture		1,000
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	(61)	$ 1	(62)
BALANCE, SHARES at Aug. 31, 2018		175,290,000
BALANCE at Aug. 31, 2018	3,482,118	$ 87,645	1,265,930	2,182,978	(54,435)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	190,311			190,311
Other Comprehensive Income (Loss), Net of Tax	298				298
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	9,654		9,654
Stock Repurchased and Retired During Period, Shares		(3,658,000)
Stock Repurchased and Retired During Period, Value	(254,328)	$ (1,829)	(26,601)	(225,898)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period		153,000
Stock Issued During Period, Value, Stock Options Exercised	7,079	$ 77	7,002
Shares Issued, Shares, Share-based Payment Arrangement, after Forfeiture		0
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	(19)	$ 0	(19)
BALANCE, SHARES at Nov. 30, 2018		171,785,000
BALANCE at Nov. 30, 2018	$ 3,435,113	$ 85,893	1,255,966	2,147,391	(54,137)
BALANCE, SHARES at Feb. 28, 2019	167,478,924	167,479,000
BALANCE at Feb. 28, 2019	$ 3,357,028	$ 83,739	1,237,153	2,104,146	(68,010)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	266,744			266,744
Other Comprehensive Income (Loss), Net of Tax	(13,196)				(13,196)
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	18,912		18,912
Stock Repurchased and Retired During Period, Shares		(2,953,000)
Stock Repurchased and Retired During Period, Value	(204,835)	$ (1,476)	(21,991)	(181,368)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period		727,000
Stock Issued During Period, Value, Stock Options Exercised	33,251	$ 363	32,888
Shares Issued, Shares, Share-based Payment Arrangement, after Forfeiture		142,000
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	(5,149)	$ 71	(5,220)
BALANCE, SHARES at May. 31, 2019		165,395,000
BALANCE at May. 31, 2019	$ 3,452,755	$ 82,697	1,261,742	2,189,522	(81,206)
BALANCE, SHARES at Feb. 28, 2019	167,478,924	167,479,000
BALANCE at Feb. 28, 2019	$ 3,357,028	$ 83,739	1,237,153	2,104,146	(68,010)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	673,499
Other Comprehensive Income (Loss), Net of Tax	$ (13,997)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	1,913,000
BALANCE, SHARES at Nov. 30, 2019	163,795,082	163,795,000
BALANCE at Nov. 30, 2019	$ 3,698,053	$ 81,897	1,321,567	2,376,596	(82,007)
BALANCE, SHARES at May. 31, 2019		165,395,000
BALANCE at May. 31, 2019	3,452,755	$ 82,697	1,261,742	2,189,522	(81,206)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	233,599			233,599
Other Comprehensive Income (Loss), Net of Tax	(10,424)				(10,424)
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	10,757		10,757
Stock Repurchased and Retired During Period, Shares		(1,526,000)
Stock Repurchased and Retired During Period, Value	(128,362)	$ (763)	(11,933)	(115,666)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period		1,008,000
Stock Issued During Period, Value, Stock Options Exercised	53,270	$ 504	52,766
Shares Issued, Shares, Share-based Payment Arrangement, after Forfeiture		9,000
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	(38)	$ 4	(42)
BALANCE, SHARES at Aug. 31, 2019		164,886,000
BALANCE at Aug. 31, 2019	3,611,557	$ 82,442	1,313,290	2,307,455	(91,630)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	173,156			173,156
Other Comprehensive Income (Loss), Net of Tax	9,623				9,623
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	8,745		8,745
Stock Repurchased and Retired During Period, Shares		(1,270,000)
Stock Repurchased and Retired During Period, Value	(114,820)	$ (635)	(10,170)	(104,015)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period		178,000
Stock Issued During Period, Value, Stock Options Exercised	9,846	$ 89	9,757
Shares Issued, Shares, Share-based Payment Arrangement, after Forfeiture		1,000
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	$ (54)	$ 1	(55)
BALANCE, SHARES at Nov. 30, 2019	163,795,082	163,795,000
BALANCE at Nov. 30, 2019	$ 3,698,053	$ 81,897	$ 1,321,567	$ 2,376,596	$ (82,007)