Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Trade Accounts receivable, allowances	$ 5,339	$ 4,073
Common Stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common Stock shares issued	175,112,496	87,566,248
Common Stock, shares outstanding	110,385,344	55,051,158
Treasury stock, shares	64,727,152	32,505,090