Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Receivables, allowance for doubtful accounts (in dollars)	$ 2,428	$ 2,004
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	83,056,668	81,329,210
Common stock, shares outstanding	80,889,275	79,161,817
Treasury stock, shares issued	2,167,393	2,167,393
Series B Preferred Stock
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Series C Preferred Stock
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	18,500	18,500
Preferred stock, shares issued	8,624	8,624
Preferred stock, shares outstanding	8,624	8,624