Condensed Consolidated Statements Of Stockholders' Equity - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-In Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total
Beginning balance at Jun. 30, 2017	$ 569	$ 1,379,130	$ (1,546,611)	$ 2,316,237	$ (189,059)	$ 1,960,266
Beginning balance, shares at Jun. 30, 2017	183,261,000		(41,086,000)
Common stock issued on exercise of options		4,682				4,682
Common stock issued on exercise of options, shares	78,000
Common stock issued on vesting of restricted stock units, net of shares withheld for tax		(195)				(195)
Common stock issued on vesting of restricted stock units, net of shares withheld for tax, shares	11,000
Stock-based compensation costs		11,959				11,959
Other comprehensive income					36,389	36,389
Net income				86,125		86,125
Dividends declared				(49,698)		(49,698)
Ending balance at Sep. 30, 2017	$ 569	1,395,576	$ (1,546,611)	2,352,664	(152,670)	2,049,528
Ending balance, shares at Sep. 30, 2017	183,350,000		(41,086,000)
Beginning balance at Jun. 30, 2017	$ 569	1,379,130	$ (1,546,611)	2,316,237	(189,059)	1,960,266
Beginning balance, shares at Jun. 30, 2017	183,261,000		(41,086,000)
Treasury stock purchases						$ (27,900)
Treasury stock purchases, shares						(300,000)
Net income						$ 205,777
Ending balance at Mar. 31, 2018	$ 571	1,424,027	$ (1,574,508)	2,372,487	(155,613)	2,066,964
Ending balance, shares at Mar. 31, 2018	184,110,000		(41,386,000)
Beginning balance at Sep. 30, 2017	$ 569	1,395,576	$ (1,546,611)	2,352,664	(152,670)	2,049,528
Beginning balance, shares at Sep. 30, 2017	183,350,000		(41,086,000)
Common stock issued on exercise of options	$ 1	7,427				7,428
Common stock issued on exercise of options, shares	394,000
Common stock issued on vesting of restricted stock units, net of shares withheld for tax	$ 1	(13,659)				(13,658)
Common stock issued on vesting of restricted stock units, net of shares withheld for tax, shares	186,000
Common stock issued on employee stock purchase plan	$ 1	8,652				8,653
Common stock issued on employee stock purchase plan, shares	148,000
Treasury stock purchases			$ (8,541)			(8,541)
Treasury stock purchases, shares			(100,000)
Stock-based compensation costs		11,997				11,997
Other comprehensive income					4,450	4,450
Net income				9,527		9,527
Dividends declared				(49,856)		(49,856)
Ending balance at Dec. 31, 2017	$ 572	1,409,993	$ (1,555,152)	2,312,335	(148,220)	2,019,528
Ending balance, shares at Dec. 31, 2017	184,078,000		(41,186,000)
Common stock issued on exercise of options		3,006				3,006
Common stock issued on exercise of options, shares	19,000
Common stock issued on vesting of restricted stock units, net of shares withheld for tax		(862)				(862)
Common stock issued on vesting of restricted stock units, net of shares withheld for tax, shares	13,000
Treasury stock purchases	$ (1)		$ (19,356)			(19,357)
Treasury stock purchases, shares			(200,000)
Stock-based compensation costs		11,890				11,890
Other comprehensive income					(7,393)	(7,393)
Net income				110,125		110,125
Dividends declared				(49,973)		(49,973)
Ending balance at Mar. 31, 2018	$ 571	1,424,027	$ (1,574,508)	2,372,487	(155,613)	2,066,964
Ending balance, shares at Mar. 31, 2018	184,110,000		(41,386,000)
Beginning balance at Jun. 30, 2018	$ 571	1,450,821	$ (1,600,412)	2,432,328	(224,328)	2,058,980
Beginning balance, shares at Jun. 30, 2018	184,316,000		(41,636,000)
Common stock issued on exercise of options		513				513
Common stock issued on exercise of options, shares	12,000
Common stock issued on vesting of restricted stock units, net of shares withheld for tax		(141)				(141)
Common stock issued on vesting of restricted stock units, net of shares withheld for tax, shares	2,000
Treasury stock purchases	$ (1)		$ (22,844)			(22,845)
Treasury stock purchases, shares			(200,000)
Stock-based compensation costs		12,476				12,476
Other comprehensive income					(12,872)	(12,872)
Net income				105,737		105,737
Dividends declared				(52,794)		(52,794)
Ending balance at Sep. 30, 2018	$ 570	1,463,669	$ (1,623,256)	2,296,473	(237,200)	1,900,256
Ending balance, shares at Sep. 30, 2018	184,330,000		(41,836,000)
Beginning balance at Jun. 30, 2018	$ 571	1,450,821	$ (1,600,412)	2,432,328	(224,328)	$ 2,058,980
Beginning balance, shares at Jun. 30, 2018	184,316,000		(41,636,000)
Common stock issued on exercise of options, shares						103,100
Treasury stock purchases						$ (22,800)
Treasury stock purchases, shares						(200,000)
Net income						$ 335,791
Ending balance at Mar. 31, 2019	$ 573	1,476,099	$ (1,623,256)	2,420,731	(252,818)	2,021,329
Ending balance, shares at Mar. 31, 2019	185,182,000		(41,836,000)
Cumulative effect of change in accounting standards				(188,798)		(188,798)
Beginning balance at Sep. 30, 2018	$ 570	1,463,669	$ (1,623,256)	2,296,473	(237,200)	1,900,256
Beginning balance, shares at Sep. 30, 2018	184,330,000		(41,836,000)
Common stock issued on exercise of options		1,263				1,263
Common stock issued on exercise of options, shares	36,000
Common stock issued on vesting of restricted stock units, net of shares withheld for tax	$ 2	(27,343)				(27,341)
Common stock issued on vesting of restricted stock units, net of shares withheld for tax, shares	623,000
Common stock issued on employee stock purchase plan	$ 1	10,575				10,576
Common stock issued on employee stock purchase plan, shares	129,000
Stock-based compensation costs		12,541				12,541
Other comprehensive income					(13,117)	(13,117)
Net income				124,639		124,639
Dividends declared				(52,773)		(52,773)
Ending balance at Dec. 31, 2018	$ 573	1,460,705	$ (1,623,256)	2,368,339	(250,317)	1,956,044
Ending balance, shares at Dec. 31, 2018	185,118,000		(41,836,000)
Common stock issued on exercise of options		2,896				2,896
Common stock issued on exercise of options, shares	55,000
Common stock issued on vesting of restricted stock units, net of shares withheld for tax		(330)				(330)
Common stock issued on vesting of restricted stock units, net of shares withheld for tax, shares	9,000
Stock-based compensation costs		12,828				12,828
Other comprehensive income					(2,501)	(2,501)
Net income				105,416		105,416
Dividends declared				(53,024)		(53,024)
Ending balance at Mar. 31, 2019	$ 573	$ 1,476,099	$ (1,623,256)	$ 2,420,731	$ (252,818)	$ 2,021,329
Ending balance, shares at Mar. 31, 2019	185,182,000		(41,836,000)