Debt (Details) $ in Thousands	Oct. 31, 2017 USD ($)
Senior Notes \| Senior Notes due October 2046
Debt Instrument [Line Items]
Aggregate principal amount	$ 125,000
Unsecured Debt
Debt Instrument [Line Items]
Debt Instrument, Periodic Payment, Principal	$ 1,563
Minimum \| Unsecured Debt
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.00%
Maximum \| Unsecured Debt
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.875%

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

No definition available.

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Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

+ Details

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

- 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.

+ Details

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Period Type:	duration

- Definition

Amount of the required periodic payments applied to principal.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

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- Details

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- Details

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Namespace Prefix:
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- Details

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- Details

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