CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Patient accounts receivable, allowance for doubtful accounts	$ 17,610	$ 20,994
Property and equipment, accumulated depreciation	120,012	113,154
Intangible assets, accumulated amortization	$ 24,560	$ 23,457
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, issued	0	0
Preferred stock, outstanding	0	0
Common Stock, par value	$ 0.001	$ 0.001
Common Stock, shares authorized	60,000,000	60,000,000
Common Stock, shares issued	32,973,576	31,876,508
Common Stock, shares outstanding	32,106,174	31,086,619
Treasury Stock at cost, shares	867,402	789,889