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, 2019			$ 1,035	$ 472,030	$ 2,066,073	$ (1,110,124)
Balance, beginning of period (value) (Accounting Standards Update 2016-13) at Jun. 30, 2019					0
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)			38,482
Shares issued for Employee Stock Purchase Plan (shares)			37,621
Shares issued for equity-based payment arrangements (value)			$ (1)	(1)
Tax withholding related to share-based compensation				(2,625)
Shares issued for Employee Stock Purchase Plan (value)				4,603
Stock-based compensation expense				6,998
Net Income	$ 161,468				161,468
Dividends					(61,502)
Purchase of treasury shares						(51,210)
Balance, end of period (value) at Dec. 31, 2019	$ 1,486,746		$ 1,036	481,005	2,166,039	(1,161,334)
Shares, end of period at Dec. 31, 2019			103,572,129
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared per share	$ 0.80
Balance, beginning of period (value) at Sep. 30, 2019			$ 1,035	475,222	2,124,672	(1,124,269)
Balance, beginning of period (value) (Accounting Standards Update 2016-13) at Sep. 30, 2019					0
Shares, beginning of period at Sep. 30, 2019			103,535,828
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued for equity-based payment arrangements (shares)			18,594
Shares issued for Employee Stock Purchase Plan (shares)			17,707
Shares issued for equity-based payment arrangements (value)			$ (1)	0
Tax withholding related to share-based compensation				(553)
Shares issued for Employee Stock Purchase Plan (value)				2,191
Stock-based compensation expense				4,145
Net Income	$ 72,098				72,098
Dividends					(30,731)
Purchase of treasury shares						(37,065)
Balance, end of period (value) at Dec. 31, 2019	$ 1,486,746		$ 1,036	481,005	2,166,039	(1,161,334)
Shares, end of period at Dec. 31, 2019			103,572,129
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared per share	$ 0.40
Preferred Shares		0
Balance, beginning of period (value) at Jun. 30, 2020	$ 1,549,688		$ 1,036	495,005	2,235,320	(1,181,673)
Balance, beginning of period (value) (Accounting Standards Update 2016-13) at Jun. 30, 2020					(493)
Shares, beginning of period at Jun. 30, 2020			103,622,563
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued for equity-based payment arrangements (shares)			78,414
Shares issued for Employee Stock Purchase Plan (shares)			35,726
Shares issued for equity-based payment arrangements (value)			$ (1)	(1)
Tax withholding related to share-based compensation				(6,689)
Shares issued for Employee Stock Purchase Plan (value)				5,138
Stock-based compensation expense				9,752
Net Income	163,198				163,198
Dividends					(65,516)
Purchase of treasury shares						(109,899)
Balance, end of period (value) at Dec. 31, 2020	$ 1,545,179		$ 1,037	503,205	2,332,509	(1,291,572)
Shares, end of period at Dec. 31, 2020			103,736,703
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared per share	$ 0.86
Balance, beginning of period (value) at Sep. 30, 2020			$ 1,037	497,030	2,293,229	(1,247,546)
Balance, beginning of period (value) (Accounting Standards Update 2016-13) at Sep. 30, 2020					0
Shares, beginning of period at Sep. 30, 2020			103,696,962
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued for equity-based payment arrangements (shares)			23,412
Shares issued for Employee Stock Purchase Plan (shares)			16,329
Shares issued for equity-based payment arrangements (value)			$ 0	0
Tax withholding related to share-based compensation				(1,184)
Shares issued for Employee Stock Purchase Plan (value)				2,232
Stock-based compensation expense				5,127
Net Income	$ 71,982				71,982
Dividends					(32,702)
Purchase of treasury shares						(44,026)
Balance, end of period (value) at Dec. 31, 2020	$ 1,545,179		$ 1,037	$ 503,205	$ 2,332,509	$ (1,291,572)
Shares, end of period at Dec. 31, 2020			103,736,703
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared per share	$ 0.43
Preferred Shares		0