Consolidated Balance Sheets (Parenthetical) (Unaudited) (USD $)	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011
Statement of Financial Position [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)	46,596,813	47,366,997	47,594,628
Common stock, outstanding (in shares)	46,596,813	47,366,997	47,594,628