CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
ASSETS
Accounts receivable, allowance	$ 20,194	$ 24,960
PROPERTY, EQUIPMENT AND FACILITIES - accumulated depreciation and amortization	122,274	111,164
OTHER ASSETS :
Noncurrent receivables, allowance	$ 1,664	$ 2,033
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)	28,548,274	28,109,987
Common stock, shares outstanding (in shares)	28,548,274	28,109,987
Treasury stock, shares (in shares)	5,910,541	5,910,541