Common Stock (Details) (USD $) In Thousands, except Share data	0 Months Ended	6 Months Ended
	May 18, 2011	Jun. 30, 2011	Jun. 30, 2010
Common Stock
public offering, common stock	6,037,500
Price per share, common stock	$ 10.70
Common Stock Purchased By Underwriters	787,500
Net proceeds from issuance of common stock	$ 62,803	$ 66,148	$ 3,314