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

The estimated value of gains (losses), net anticipated to be transferred in the future from accumulated other comprehensive income into earnings.

+ References

No definition available.

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- Definition

The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4D
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624177-113959

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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.

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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://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5579245-113959

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- Definition

Period the derivative contract is outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

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- Definition

Number of interest rate derivative instruments held by the entity at the reporting date.

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Derivatives and Hedging Instruments - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2017 AUD ($) instrument contract	Dec. 31, 2017 USD ($) instrument contract	Dec. 31, 2017 GBP (£) instrument contract
Derivative [Line Items]
Number of interest rate cap contracts \| contract				2	2	2
Foreign currency exchange contracts
Derivative [Line Items]
Gain (loss) reclassified from OCI into earnings		$ 0	$ 0
Interest rate cap contracts
Derivative [Line Items]
Derivative instrument, notional amount					$ 405,300,000	£ 300,000,000
Cash Flow Hedges
Derivative [Line Items]
Derivative number of instruments held \| instrument				2	2	2
Cash Flow Hedges \| Foreign currency exchange contracts
Derivative [Line Items]
Derivative instrument, notional amount					$ 12,600,000
Net derivative gain (loss) included in OCI to be reclassified into earnings	$ 1,900,000
Gain (loss) reclassified from OCI into earnings	$ 0
Cash Flow Hedges \| Interest rate swap agreements
Derivative [Line Items]
Derivative instrument, notional amount				$ 30.0	$ 23,400,000
Minimum \| Derivatives Not Designated as Hedging Instruments \| Cash Flow Hedges
Derivative [Line Items]
Derivative term of contract	1 month
Maximum \| Derivatives Not Designated as Hedging Instruments \| Cash Flow Hedges
Derivative [Line Items]
Derivative term of contract	3 months