Condensed Consolidated Statements Of Changes In Equity - USD ($) shares in Thousands, $ in Thousands	Common Stock [Member]	Additional Paid-In Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member] Cumulative Effect Of Change In Accounting Standards [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Cumulative Effect Of Change In Accounting Standards [Member]	Total
Beginning balance at Jun. 30, 2019	$ 575	$ 1,511,473	$ (1,623,256)		$ 2,436,410	$ (253,009)		$ 2,072,193
Beginning balance, shares at Jun. 30, 2019	185,491		(41,836)
Common stock issued on exercise of options		5,609						5,609
Common stock issued on exercise of options, shares	110
Common stock issued on vesting of restricted stock units, net of shares withheld for tax		(327)						(327)
Common stock issued on vesting of restricted stock units, net of shares withheld for tax, shares	4
Stock-based compensation costs		13,256						13,256
Other comprehensive income						(37,576)		(37,576)
Net income					120,148			120,148
Dividends declared					(56,052)			(56,052)
Ending balance at Sep. 30, 2019	$ 575	1,530,011	$ (1,623,256)		2,500,506	(290,585)		2,117,251
Ending balance, shares at Sep. 30, 2019	185,605		(41,836)
Beginning balance at Jun. 30, 2019	$ 575	1,511,473	$ (1,623,256)		2,436,410	(253,009)		2,072,193
Beginning balance, shares at Jun. 30, 2019	185,491		(41,836)
Net income								280,702
Ending balance at Dec. 31, 2019	$ 578	1,521,992	$ (1,623,256)		2,604,910	(246,118)		2,258,106
Ending balance, shares at Dec. 31, 2019	186,435		(41,836)
Beginning balance at Sep. 30, 2019	$ 575	1,530,011	$ (1,623,256)		2,500,506	(290,585)		2,117,251
Beginning balance, shares at Sep. 30, 2019	185,605		(41,836)
Common stock issued on exercise of options		6,498						6,498
Common stock issued on exercise of options, shares	117
Common stock issued on vesting of restricted stock units, net of shares withheld for tax	$ 3	(40,764)						(40,761)
Common stock issued on vesting of restricted stock units, net of shares withheld for tax, shares	576
Common stock issued on employee stock purchase plan		12,190						12,190
Common stock issued on employee stock purchase plan, shares	137
Stock-based compensation costs		14,057						14,057
Other comprehensive income						44,467		44,467
Net income					160,554			160,554
Dividends declared					(56,150)			(56,150)
Ending balance at Dec. 31, 2019	$ 578	1,521,992	$ (1,623,256)		2,604,910	(246,118)		2,258,106
Ending balance, shares at Dec. 31, 2019	186,435		(41,836)
Beginning balance at Jun. 30, 2020	$ 580	1,570,694	$ (1,623,256)		2,832,991	(283,982)		2,497,027
Beginning balance, shares at Jun. 30, 2020	186,723		(41,836)
Common stock issued on exercise of options		1,026						1,026
Common stock issued on exercise of options, shares	18
Common stock issued on vesting of restricted stock units, net of shares withheld for tax		227						227
Common stock issued on vesting of restricted stock units, net of shares withheld for tax, shares	3
Stock-based compensation costs		16,071						16,071
Other comprehensive income						43,791		43,791
Net income					178,372			178,372
Dividends declared					(56,511)			(56,511)
Ending balance at Sep. 30, 2020	$ 580	1,588,018	$ (1,623,256)	$ (1,143)	2,953,709	(240,191)	$ (1,143)	2,678,860
Ending balance, shares at Sep. 30, 2020	186,744		(41,836)
Beginning balance at Jun. 30, 2020	$ 580	1,570,694	$ (1,623,256)		2,832,991	(283,982)		2,497,027
Beginning balance, shares at Jun. 30, 2020	186,723		(41,836)
Net income								357,886
Ending balance at Dec. 31, 2020	$ 582	1,574,240	$ (1,623,256)		3,076,569	(163,151)		2,864,984
Ending balance, shares at Dec. 31, 2020	187,340		(41,836)
Beginning balance at Sep. 30, 2020	$ 580	1,588,018	$ (1,623,256)	$ (1,143)	2,953,709	(240,191)	$ (1,143)	2,678,860
Beginning balance, shares at Sep. 30, 2020	186,744		(41,836)
Common stock issued on exercise of options		1,857						1,857
Common stock issued on exercise of options, shares	29
Common stock issued on vesting of restricted stock units, net of shares withheld for tax	$ 2	(46,734)						(46,732)
Common stock issued on vesting of restricted stock units, net of shares withheld for tax, shares	451
Common stock issued on employee stock purchase plan		15,729						15,729
Common stock issued on employee stock purchase plan, shares	116
Stock-based compensation costs		15,370						15,370
Other comprehensive income						77,040		77,040
Net income					179,514			179,514
Dividends declared					(56,654)			(56,654)
Ending balance at Dec. 31, 2020	$ 582	$ 1,574,240	$ (1,623,256)		$ 3,076,569	$ (163,151)		$ 2,864,984
Ending balance, shares at Dec. 31, 2020	187,340		(41,836)