Preferred Stock Rights (Details)	6 Months Ended
	Jun. 30, 2015 $ / shares	Dec. 31, 2014 $ / shares	Mar. 21, 2011 shares Right $ / shares
Preferred Stock Rights
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred Stock Rights Agreement [Member]
Preferred Stock Rights
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 (per right) | Right			1
Common stock, par value (in dollars per share)			$ 0.01
Number of rights issued with each issuance of common stock (per right) | Right			1
Term of stockholder protection rights agreement	3 years
Rights Agreement Amendment Date	Mar. 21, 2014
Term of the Rights Agreement extension	2 years
Rights Agreement Expiration Date	Mar. 21, 2016
Fraction of participating preferred stock that can be exercised as a result of right | shares			0.01
Exercise price of right (in dollars per share)			$ 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) | shares			1
Percentage of common stock acquired to cause substantial dilution (in hundredths)			20.00%