Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

+ Details

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Namespace Prefix:	invest_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

The per share amount of a dividend declared, but not paid, as of the financial reporting date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4304-108586

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	na
Period Type:	instant

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_ForeignExchangeForwardMember
Namespace Prefix:
Data Type:	na
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Period Type:

- Details

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Namespace Prefix:
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Subsequent Events (Details) £ in Millions	Apr. 25, 2019 $ / shares	Apr. 10, 2019 GBP (£)	Mar. 31, 2019 GBP (£)	Dec. 31, 2018 GBP (£)
Foreign Currency Forward
Subsequent Event [Line Items]
Notional amount			£ 46.0	£ 46.0
Subsequent Event
Subsequent Event [Line Items]
Dividend declared (usd per share) \| $ / shares	$ 0.27
Subsequent Event \| Foreign Currency Forward
Subsequent Event [Line Items]
Notional amount		£ 16.0