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 [Abstract]
Net earnings	$ 43,369	$ 39,781	$ 71,805	$ 33,973	$ (90,515)	$ 80,904	$ 32,519	$ 11,029	$ 188,928	$ 33,937	$ 136,791
Basic average shares outstanding									44,617	44,606	44,522
Dilutive effect of stock options and equivalents									830	751	801
Diluted average shares outstanding									45,447	45,357	45,323
Earnings per share
Basic earnings per share (in dollars per share)	$ 0.97	$ 0.89	$ 1.61	$ 0.76	$ (2.03)	$ 1.81	$ 0.73	$ 0.25	$ 4.23	$ 0.76	$ 3.07
Diluted earnings per share (in dollars per share)	$ 0.95	$ 0.87	$ 1.58	$ 0.75	$ (2.03)	$ 1.79	$ 0.72	$ 0.24	$ 4.16	$ 0.75	$ 3.02
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities, shares									300	1,300	900
Antidilutive securities, weighted average exercise price									$ 54.28	$ 49.02	$ 50.52