The amount of the additional liability or refund received or expected based on a final settlement with a taxing authority.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15A
-Subparagraph (3)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=SL6600010-109319

Name:	us-gaap_IncomeTaxExaminationLiabilityRefundAdjustmentFromSettlementWithTaxingAuthority
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Commitments and Contingencies (Details) £ in Millions, $ in Millions	Sep. 30, 2019 USD ($)	Nov. 30, 2018 GBP (£)	Dec. 31, 2017 USD ($)
Loss Contingencies [Line Items]
Surety bond, notional amount \| £		£ 92
Surety bond exposure, liability	$ 6
Foreign Tax Authority \| UK Government
Loss Contingencies [Line Items]
Income taxes paid from settlement with taxing authority			$ 108