Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2012	Dec. 31, 2011
Condensed Consolidated Balance Sheets [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Series A convertible participating preferred stock, shares issued	0	0
Series A convertible participating preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.002	$ 0.002
Common stock, shares authorized	175,000,000	175,000,000
Common stock, shares outstanding	69,717,726	70,568,501
Treasury stock, shares	10,765,183	9,159,083