CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) (USD $) In Thousands, except Share data	Jun. 30, 2011	Dec. 31, 2010
CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical)
Accounts receivable, allowance	$ 20,560	$ 24,960
PROPERTY, EQUIPMENT AND FACILITIES, net of accumulated depreciation and amortization	116,350	111,164
Noncurrent receivables, allowance	$ 1,662	$ 2,033
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)	28,499,673	28,109,987
Common stock, shares outstanding (in shares)	28,499,673	28,109,987
Treasury stock, shares (in shares)	5,910,541	5,910,541