Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Consolidated Balance Sheets [Abstract]
Allowance for doubtful accounts, accounts receivable	$ 105	$ 2,838
Preferred shares, par value	$ 0.1	$ 0.1
Preferred shares, shares authorized	5,000	5,000
Preferred shares, issued
Common stock, par value	$ 0.1	$ 0.1
Common stock, shares authorized	145,000	145,000
Common stock, issued	49,143	49,330
Common stock, outstanding	49,143	49,330