CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Patient accounts receivable, allowance for doubtful accounts	$ 19,603	$ 17,438
Property and equipment, accumulated depreciation	96,891	94,266
Intangible assets, accumulated amortization	$ 22,024	$ 20,611
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, issued
Preferred stock, outstanding
Common Stock, par value	$ 0.001	$ 0.001
Common Stock, shares authorized	60,000,000	60,000,000
Common Stock, shares issued	32,110,141	31,017,363
Common Stock, shares outstanding	31,328,783	30,328,549
Treasury Stock at cost, shares	781,358	688,814