Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Allowances for doubtful accounts	$ 4,084	$ 4,072
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	79,568,496	79,008,243
Treasury stock, shares	29,990	29,990
Series A Convertible Preferred Stock [Member]
Preferred Stock, par value	$ 0.001	$ 0.001
Preferred Stock, shares authorized	1,000,000	1,000,000
Preferred Stock, shares issued	39,442	39,442
Preferred Stock, shares outstanding	39,442	39,442