Income Taxes Income Taxes (Details) - Unrecognized Tax Benefits (USD $)
In Thousands, unless otherwise specified
3 Months Ended 12 Months Ended
Mar. 31, 2013
Dec. 31, 2013
Dec. 31, 2012
Income Tax [Abstract]      
Balance as of January 1, $ 1,136 $ 1,136 $ 369
Gross increase related to current period tax positions   1,043 767
Gross decrease related to prior period tax positions (143)   0
Balance as of December 31,   $ 2,036 $ 1,136