Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Statement of Financial Position [Abstract]
Accounts receivables, allowance for doubtful accounts	$ 8,777	$ 11,562
Common stock, par value	$ 0.10	$ 0.10
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	32,009,286	31,435,264
Treasury stock, shares	1,260,879	655,802