Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2011	Dec. 31, 2010
Consolidated Balance Sheets
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares issued	36,217,914	33,373,410
Common Stock, Shares, Outstanding	28,742,906	27,275,936
Treasury stock, shares	7,475,008	6,097,474