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Income Taxes (Tax Cuts and Jobs Act of 2017) (Details) - USD ($) $ in Millions |  |  | 12 Months Ended
--- | --- | --- | ---
Dec. 22, 2017 | Dec. 21, 2017 | Dec. 31, 2018 | Dec. 31, 2017
Tax Cuts and Jobs of Act 2017 [Line Items] |  |  |  |
U.S. statutory rate (as a percent) | 21.00% | 35.00% |  | 35.00%
Unites States |  |  |  |
Tax Cuts and Jobs of Act 2017 [Line Items] |  |  |  |
Tax Cuts And Jobs Act Of 2017, Incomplete Accounting, Change In Tax Rate, Deferred Tax Asset, Provisional Income Tax Expense |  |  |  | $ 43.1
Forecast |  |  |  |
Tax Cuts and Jobs of Act 2017 [Line Items] |  |  |  |
Percentage of utilization of net operating losses |  |  | 80.00% |

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- Definition Percentage of domestic federal statutory tax rate applicable to pretax income (loss). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32687-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 6.I) -URI http://asc.fasb.org/extlink&oid=34349781&loc=d3e330036-122817 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 13 -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32698-109319 + Details
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