CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY Statement - USD ($) $ in Thousands	Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]
Balance, beginning of period (value) at Jun. 30, 2018			$ 1,033	$ 464,138	$ 1,912,933	$ (1,055,260)
Shares, beginning of period at Jun. 30, 2018			103,278,562
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued for equity-based payment arrangements (shares)			120,119
Shares issued for equity-based payment arrangements (value)			$ (1)	(1)
Tax withholding related to share-based compensation				(13,797)
Shares issued for Employee Stock Purchase Plan (shares)			56,208
Shares issued for Employee Stock Purchase Plan (value)			$ 1	6,658
Stock-based compensation expense				8,651
Net Income	$ 210,892				210,892
Dividends					(87,970)
Purchase of treasury shares						(21,276)
Balance, end of period (value) at Mar. 31, 2019	$ 1,426,003		$ 1,035	465,649	2,035,855	(1,076,536)
Shares, end of period at Mar. 31, 2019			103,454,889
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared per share	$ 1.14
Balance, beginning of period (value) at Dec. 31, 2018			$ 1,034	459,988	2,007,469	(1,076,536)
Shares, beginning of period at Dec. 31, 2018			103,428,416
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued for equity-based payment arrangements (shares)			4,722
Shares issued for equity-based payment arrangements (value)			$ 0	0
Tax withholding related to share-based compensation				(313)
Shares issued for Employee Stock Purchase Plan (shares)			21,751
Shares issued for Employee Stock Purchase Plan (value)			$ 1	2,469
Stock-based compensation expense				3,505
Net Income	$ 59,252				59,252
Dividends					(30,866)
Purchase of treasury shares						0
Balance, end of period (value) at Mar. 31, 2019	$ 1,426,003		$ 1,035	465,649	2,035,855	(1,076,536)
Shares, end of period at Mar. 31, 2019			103,454,889
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared per share	$ 0.40
Preferred Shares		0
Balance, beginning of period (value) at Jun. 30, 2019	$ 1,429,013		$ 1,035	472,029	2,066,073	(1,110,124)
Shares, beginning of period at Jun. 30, 2019			103,496,026
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued for equity-based payment arrangements (shares)			47,098
Shares issued for equity-based payment arrangements (value)			$ 0	0
Tax withholding related to share-based compensation				(3,328)
Shares issued for Employee Stock Purchase Plan (shares)			56,520
Shares issued for Employee Stock Purchase Plan (value)			$ 1	7,200
Stock-based compensation expense				11,689
Net Income	235,323				235,323
Dividends					(94,486)
Purchase of treasury shares						(71,549)
Balance, end of period (value) at Mar. 31, 2020	$ 1,513,863		$ 1,036	487,590	2,206,910	(1,181,673)
Shares, end of period at Mar. 31, 2020			103,599,644
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared per share	$ 1.23
Balance, beginning of period (value) at Dec. 31, 2019			$ 1,036	481,005	2,166,039	(1,161,334)
Shares, beginning of period at Dec. 31, 2019			103,572,129
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued for equity-based payment arrangements (shares)			8,616
Shares issued for equity-based payment arrangements (value)			$ 0	0
Tax withholding related to share-based compensation				(703)
Shares issued for Employee Stock Purchase Plan (shares)			18,899
Shares issued for Employee Stock Purchase Plan (value)			$ 0	2,597
Stock-based compensation expense				4,691
Net Income	$ 73,855				73,855
Dividends					(32,984)
Purchase of treasury shares						(20,339)
Balance, end of period (value) at Mar. 31, 2020	$ 1,513,863		$ 1,036	$ 487,590	$ 2,206,910	$ (1,181,673)
Shares, end of period at Mar. 31, 2020			103,599,644
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared per share	$ 0.43
Preferred Shares		0