Stockholders' Equity (Details) (USD $) In Millions, except Share data, unless otherwise specified	6 Months Ended	1 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2014 Second Public Offering [Member]	Jun. 30, 2014 Option to purchase additional shares granted to the underwriters [Member]	Jun. 30, 2014 Maximum [Member]
Subsidiary, Sale of Stock [Line Items]
Common stock authorized for issuance under prior shelf registration statement with SEC, dollar amount				$ 50
Available proceeds under ATM	15
Shares sold		28,750,000	3,750,000
Sales per share price range		$ 4.00
Proceeds from shares sold		$ 108