CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Patient accounts receivable, allowance for doubtful accounts	$ 14,956	$ 14,231
Property and equipment, accumulated depreciation	140,705	129,891
Intangible assets, accumulated amortization	$ 25,354	$ 25,133
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	34,153,969	33,413,970
Common stock, shares outstanding	33,195,927	32,538,971
Treasury stock at cost, shares	958,042	874,999