Income Taxes (Details) (USD $)
In Thousands, unless otherwise specified
3 Months Ended 9 Months Ended
Sep. 30, 2013
Sep. 30, 2012
Sep. 30, 2013
Sep. 30, 2012
Income Taxes        
Income tax expense $ 103 $ 0 $ 132 $ 0
Effective income tax rate (as a percent) 6.00% 0.00% 10.00% 0.00%
U.S. federal statutory rate (as a percent) 34.00%   34.00%