Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Sep. 30, 2016	Jun. 30, 2016
Current assets:
Receivables, allowance	$ 931	$ 831
Property, plant and equipment, accumulated depreciation	450,241	438,991
Intangible assets, accumulated amortization	64,305	63,304
Other long term assets, accumulated amortization	$ 1,594	$ 1,560
Stockholders' equity:
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	300,000	300,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	2,000,000	2,000,000
Common stock, shares outstanding (in shares)	39,762	39,736
Treasury stock (in shares)	5,556	5,556