Fair value of all derivative liabilities designated as fair value hedging instruments.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624163-113959

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

Derivative Financial Instruments - Narrative (Details) - 3 months ended Mar. 31, 2019 £ in Millions, $ in Millions	USD ($)	GBP (£)
Net Investment \| Facility and 2015 Term Loan
Derivative [Line Items]
Borrowings designated as hedge of net investment \| £		£ 55
Interest-rate swap contracts \| Maximum
Derivative [Line Items]
Estimate change in fair value of derivative for assumption of one percentage point change in the interest rate \| $	$ 1