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

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

The number of derivative instruments of a particular group held by the entity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5579245-113959

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5580258-113959

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Derivative Financial Instruments - Summary of Non-designated Hedges (Detail) - Not Designated as Hedging Instrument [Member] € in Thousands, £ in Thousands, $ in Thousands, $ in Thousands	Mar. 31, 2019 EUR (€) DerivativeInstrument	Mar. 31, 2019 CAD ($) DerivativeInstrument	Dec. 31, 2018 EUR (€) DerivativeInstrument	Dec. 31, 2018 GBP (£) DerivativeInstrument	Dec. 31, 2018 AUD ($) DerivativeInstrument
AUD [Member] \| Buy AUD / Sell USD Forward [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Number of Instruments			1	1	1
Notional Amount \| $					$ 55,000
AUD [Member] \| Buy USD / Sell AUD Forward [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Number of Instruments			1	1	1
Notional Amount \| $					$ 55,000
GBP [Member] \| Buy GBP / Sell USD Forward [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Number of Instruments			1	1	1
Notional Amount \| £				£ 23,200
GBP [Member] \| Buy USD / Sell GBP Forward [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Number of Instruments			1	1	1
Notional Amount \| £				£ 23,200
EUR [Member] \| Buy GBP / Sell EUR Forward [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Number of Instruments	1	1	1	1	1
Notional Amount \| €	€ 12,857		€ 12,857
CAD [Member] \| Buy USD / Sell CAD Forward [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Number of Instruments	1	1
Notional Amount \| $		$ 4,200
CAD [Member] \| Buy CAD / Sell USD Forward [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Number of Instruments	1	1
Notional Amount \| $		$ 4,200