CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Patient accounts receivable, allowance for doubtful accounts	$ 17,716	$ 16,526
Property and equipment, accumulated depreciation	138,650	141,793
Intangible assets, accumulated amortization	$ 27,864	$ 25,386
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	35,253,577	34,786,966
Common Stock, shares outstanding	33,597,215	33,607,282
Treasury Stock at cost, shares	1,656,362	1,179,684