CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Allowance for doubtful accounts	$ 7,526	$ 4,718
Preferred stock, par value	$ 1	$ 1
Preferred stock, shares authorized	250,000	250,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.1	$ 0.1
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares outstanding	58,206,813	62,143,572
Treasury stock, shares	6,374,882	2,008,986