CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
CONSOLIDATED BALANCE SHEETS
Accounts receivable, allowance (in dollars)	$ 1,028	$ 830
Accounts receivable, allowance for appeals (in dollars)	$ 8,545	$ 6,985
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	125,000,000	125,000,000
Common stock, shares issued	92,984,526	92,374,539
Common stock, shares outstanding	87,559,679	86,949,692
Treasury stock, shares	5,424,847	5,424,847