Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Trade accounts receivable, allowance	$ 1,523	$ 0
Current liabilities:
Current portion of long-term debt, discount	1,657
Discounts and deferred debt costs, long-term debt	$ 10,244	$ 17,344
Stockholders' equity:
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, authorized (in shares)	5,000,000	5,000,000
Preferred stock, outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, authorized (in shares)	80,000,000	80,000,000
Common stock, issued (in shares)	26,371,572	26,095,431
Common stock, outstanding (in shares)	26,219,129	25,998,844
Treasury stock (in shares)	152,443	96,587