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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

X

- Definition

Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32537-109319

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- Definition

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+ References

No definition available.

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X

- 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

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