CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
ASSETS
Accounts receivable, allowance	$ 17,751	$ 20,194
PROPERTY, EQUIPMENT AND FACILITIES - accumulated depreciation and amortization	137,834	122,274
OTHER ASSETS :
Noncurrent receivables, allowance	$ 1,078	$ 1,664
LIABILITIES AND STOCKHOLDERS' EQUITY
Preferred stock, par value (in dollars per share)	$ 0	$ 0
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0	$ 0
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	29,659,457	28,548,274
Common stock, shares outstanding (in shares)	29,659,457	28,548,274
Treasury stock, shares (in shares)	5,910,541	5,910,541