Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Accounts receivable, allowance for doubtful accounts	$ 620	$ 495
Property and equipment, accumulated depreciation	$ 143,662	$ 135,484
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	35,000,000	35,000,000
Common stock, shares issued (in shares)	11,324,917	11,193,813