Preferred Stock Rights (Details) (USD $)	6 Months Ended
	Jun. 30, 2012	Dec. 31, 2011	Mar. 21, 2011
Preferred Stock Rights [Abstract]
Date on which dividends payable was declared by Board of Directors	Mar. 21, 2011
Number of preferred stock purchase right declared for each outstanding common stock			1
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Number of rights issued with each issuance of common stock			1
Term of stockholder protection rights agreement (in years)			3Y
Maximum period that can be extended for right plan (in years)			3 years 0 months 0 days
Fraction of participating preferred stock that can be exercised as a result of right			0.01
Exercise price of right			$ 8.00
Minimum percentage of common stock owned for right to become exercisable (in hundredths)			20.00%
Redemption price per right (in dollars per share)			$ 0.001
Number of common stock exchange for rights (in shares)			1
Percentage of common stock acquired to cause substantial dilution (in hundredths)			20.00%