Significant Accounting Policies - Long-lived Asset Impairment and Foreign Exchange Gains Losses (Details) - USD ($) $ in Millions	1 Months Ended	11 Months Ended	12 Months Ended
Dec. 31, 2018	Nov. 19, 2018	Dec. 31, 2019	Dec. 31, 2017
Significant Accounting Policies
Long-lived asset impairments	$ 0.0	$ 0.0	$ 0.0	$ 0.0
Deferred certification and major maintenance costs	0.5		9.8
Foreign exchange losses	$ (0.1)	$ (0.1)	$ (0.7)	$ (0.7)

The aggregate amount of write-downs for impairments recognized during the period for long lived assets held for use (including those held for disposal by means other than sale).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 45
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 958
-SubTopic 220
-Section 45
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration