Consolidated Balance Sheets Parenthetical (Unaudited) (USD $)	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 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)	47,616,144	47,366,997	48,298,621
Common stock, outstanding (in shares)	47,616,144	47,366,997	48,298,621