Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Consolidated Balance Sheets [Abstract]
Allowances for patient receivables, current	$ 1,035	$ 1,392
Allowances for patient receivables, non-current	$ 634	$ 330
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares issued	25,291,637	25,291,637
Common stock, shares outstanding	18,858,147	18,711,365
Treasury stock, shares	6,433,490	6,580,272