Income Taxes, Change in Deferred Tax Valuation Allowance (Details 2) - Income tax valuation allowance - USD ($) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
|
| Valuation allowance | |||
| Balance at Beginning of Period | $ 44,309 | $ 34,921 | $ 23,864 |
| Additions Charged to Expense/Against Revenue | 10,430 | 9,388 | 11,057 |
| Balance at End of Period | $ 54,739 | $ 44,309 | $ 34,921 |