CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2018	Jun. 30, 2018
Statement of Financial Position [Abstract]
Accounts receivable, allowance for doubtful accounts	$ 0	$ 0
Property and equipment, accumulated depreciation	$ 31,449	$ 30,858
Common stock (in usd per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	250,000,000	250,000,000
Common stock, shares issued (in shares)	187,143,000	186,801,000
Common stock, shares outstanding (in shares)	187,079,000	186,766,000
Treasury stock, shares (in shares)	64,000	35,000