v3.8.0.1

Condensed Consolidating Financial Information - Additional Information (Detail) - USD ($)	Sep. 30, 2017	Mar. 17, 2014
Supplemental Guarantor Financial Information [Line Items]
Ownership percentage in domestic subsidiaries	100.00%
5.25% Senior Notes due March 15, 2019 [Member] | Senior Notes [Member]
Supplemental Guarantor Financial Information [Line Items]
Senior notes, amount issued		$ 500,000,000
Interest rate on Senior Notes	5.25%	5.25%

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- Definition

Supplemental Guarantor Financial Information [Line Items]

+ References

No definition available.

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- 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

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
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-Section 45
-Paragraph 2
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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ 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(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

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