Net Income Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2016
Treasury Stock, Value, Acquired, Cost Method									$ 200,000	$ 375,000	$ 180,066
Net Income (Loss) Attributable to Parent	$ 38,020	$ 37,835	$ 38,078	$ 34,755	$ 54,352	$ 35,834	$ 37,010	$ 35,000	$ 148,688	$ 162,196	$ 139,951
Weighted Average Number of Shares Outstanding, Basic	71,349,000	71,828,000	72,342,000	73,024,000	74,294,000	75,676,000	76,905,000	79,048,000	72,140,000	76,491,000	82,892,000
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements									816,000	487,000	417,000
Weighted Average Number of Shares Outstanding, Diluted	72,315,000	72,663,000	73,036,000	73,609,000	74,830,000	76,182,000	77,318,000	79,385,000	72,956,000	76,978,000	83,309,000
Earnings Per Share, Basic	$ 0.53	$ 0.53	$ 0.53	$ 0.48	$ 0.73	$ 0.47	$ 0.48	$ 0.44	$ 2.06	$ 2.12	$ 1.69
Earnings Per Share, Diluted	$ 0.53	$ 0.52	$ 0.52	$ 0.47	$ 0.73	$ 0.47	$ 0.48	$ 0.44	$ 2.04	$ 2.11	$ 1.68
Employee Stock Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount									32,609
Stock Compensation Plan [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount									419,000	525,000	1,028,000
Employee Stock Option [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit									$ 75.74
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit									$ 93.59
Accelerated Share Repurchase Program [Member]
Treasury Stock, Value, Acquired, Cost Method										$ 100,000