Condensed Consolidated Balance Sheets (Parenthetical) (Unaudited) (USD $)	Jun. 30, 2012	Dec. 31, 2011
Condensed Consolidated Balance Sheets [Abstract]
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	118,412,337	117,593,329
Common stock, shares outstanding	114,873,675	114,201,737
Treasury stock, shares	3,538,662	3,391,592