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Income Taxes (Income Tax Reconciliation) (Details) | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Income Tax Disclosure [Abstract] |  |  |
Statutory rate | 21.00% | 34.00% | 34.00%
State and local taxes | 1.50% | 1.50% | 1.60%
Uncertain tax position | 72.90% | 0.00% | 0.00%
Research and development credit | (48.30%) | 0.00% | (7.50%)
Stock based compensation | (5.20%) | (13.40%) | 0.30%
Nondeductible compensation | 4.10% |  |
Domestic production credit | 0.00% | (14.30%) | (5.40%)
Other | (2.70%) | (1.50%) | 0.60%
Effective rate | 43.30% | 6.30% | 23.60%
Deferred re-measurement for rate change | 0.00% | (1144.40%) | 0.00%
Effective rate | 43.30% | (1138.10%) | 23.60%

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- Definition Percentage of increase (decrease) in effective tax rate for measurement period adjustment from accounting for tax effect pursuant to Tax Cuts and Jobs Act of 2017. + References No definition available. + Details
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