Consolidated Balance Sheets (Parenthetical) (Unaudited) (USD $)	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011
Consolidated Balance Sheets [Abstract]
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001	$ 0.001
Common stock, authorized (in shares)	100,000,000	100,000,000	100,000,000
Common stock, shares issued (in shares)	46,653,782	47,366,997	48,253,576
Common stock, outstanding (in shares)	46,653,782	47,366,997	48,253,576