CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
CONSOLIDATED BALANCE SHEETS
Accounts receivable, allowance for doubtful accounts (in dollars)	$ 21,379	$ 22,028
Patents and other intangible assets, accumulated amortization (in dollars)	$ 20,643	$ 15,160
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	60,000,000	60,000,000
Common stock, shares issued	35,617,884	35,127,230
Common stock, shares outstanding	35,617,884	35,127,230
Treasury stock, shares	141,154	141,154