Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data	Sep. 30, 2011	Dec. 31, 2010
Condensed Consolidated Balance Sheets [Abstract]
Allowances for patient receivables, current	$ 1,124	$ 1,392
Allowances for patient receivables, non-current	$ 595	$ 330
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares issued	25,291,637	25,291,637
Common stock, shares outstanding	18,849,527	18,711,365
Treasury stock, shares	6,442,110	6,580,272