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Income Taxes - Narrative (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Mar. 31, 2019 | Dec. 31, 2019 | Dec. 31, 2020
Operating Loss Carryforwards [Line Items] |  |  |
Tax cuts and jobs act | $ 1.3 | $ 1.3 |
Valuation allowance |  | $ 492.4 | $ 499.4
All U.S. and Portion of Icelandic Deferred Tax Assets [Member] |  |  |
Operating Loss Carryforwards [Line Items] |  |  |
Valuation allowance |  |  | $ 499.4

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- Definition Amount of increase (decrease) in accumulated other comprehensive income (AOCI) for reclassification to retained earnings of tax effect from remeasurement of deferred tax pursuant to Tax Cuts and Jobs Act. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 12A -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121641772&loc=SL116659650-108580 + Details
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