Consolidated Balance Sheets (Parenthetical) - $ / shares shares in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stockholders' equity:
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	85,000	85,000
Common stock, shares issued (in shares)	46,410	46,410
Common stock, shares outstanding (in shares)	40,738	40,738	40,738
Treasury stock, at cost (in shares)	5,672	5,672	5,672