Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2015
Earnings Per Share, Basic and Diluted [Abstract]
Net Income	$ 64,691	$ 60,044	$ 58,814	$ 62,244	$ 84,270	$ 53,883	$ 59,348	$ 51,366	$ 245,793	$ 248,867	$ 211,221
Common share information:
Basic weighted average shares outstanding	77,602	77,597	77,814	78,413	78,841	78,805	79,473	80,545	77,856	79,416	81,353
Dilutive effect of stock options and restricted stock									399	318	248
Diluted weighted average shares outstanding	78,064	77,932	78,180	78,844	79,261	79,167	79,770	80,735	78,255	79,734	81,601
Basic earnings per share	$ 0.83	$ 0.77	$ 0.76	$ 0.79	$ 1.07	$ 0.68	$ 0.75	$ 0.64	$ 3.16	$ 3.13	$ 2.60
Diluted earnings per share	$ 0.83	$ 0.77	$ 0.75	$ 0.79	$ 1.06	$ 0.68	$ 0.74	$ 0.64	$ 3.14	$ 3.12	$ 2.59
Antidilutive stock options and restricted stock excluded from computation of earnings per share									32	0	0