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

Subsequent events (Details) - USD ($) $ in Millions		1 Months Ended		5 Months Ended	12 Months Ended
Subsequent events (Details) - USD ($) $ in Millions	Apr. 03, 2020	Apr. 30, 2020	Mar. 31, 2020	Jun. 12, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Subsequent Event [Line Items]
Repayments of long term debt					$ 192.6	$ 296.4	$ 215.0
Subsequent Event \| Drilling rigs
Subsequent Event [Line Items]
Impairment expense				$ 922.9
Subsequent Event \| T-15 \| Secured Debt \| Seadrill Limited \| Tender Rig Facility
Subsequent Event [Line Items]
Repayments of long term debt	$ 15.9	$ 15.9	$ 2.7