Revolving Line of Credit - Additional Information (Detail)	3 Months Ended
Dec. 31, 2015 USD ($)
Line of Credit Facility [Line Items]
Unsecured revolving line of credit	$ 400,000,000
Revolving credit facility, expiration date	Dec. 30, 2019
Revolving credit facility, interest rate description	Interest on amounts borrowed under the credit facility is based on (i) a base rate, which is the greater of (a) the prime rate, (b) the Federal Funds rate plus 0.500% and (c) the one-month LIBOR rate plus 1.000%, plus, in each case, an applicable margin, or (ii) an adjusted LIBOR rate plus an applicable margin. The applicable margin for base rate borrowings ranges from 0% to 0.875% and for LIBOR borrowings ranges from 1.000% to 1.875%, and is determined based on our consolidated leverage ratio
Credit facility restrictive covenant, minimum fixed charge ratio	2.5
Credit facility restrictive covenant, maximum consolidated leverage ratio	3.0
Credit facility restrictive covenant, maximum consolidated leverage ratio step up	3.5
Borrowings outstanding	$ 243,000,000
Interest rate of borrowings outstanding	1.756%
Federal Fund Rate
Line of Credit Facility [Line Items]
Debt instrument basis spread on variable rate	0.50%
Libor
Line of Credit Facility [Line Items]
Debt instrument basis spread on variable rate	1.00%
Libor \| Minimum
Line of Credit Facility [Line Items]
Debt instrument basis spread on variable rate	1.00%
Libor \| Maximum
Line of Credit Facility [Line Items]
Debt instrument basis spread on variable rate	1.875%
Base Rate \| Minimum
Line of Credit Facility [Line Items]
Debt instrument basis spread on variable rate	0.00%
Base Rate \| Maximum
Line of Credit Facility [Line Items]
Debt instrument basis spread on variable rate	0.875%
Long-term Debt
Line of Credit Facility [Line Items]
Borrowings outstanding	$ 200,000,000

Fixed Charge Coverage Ratio, Minimum

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- Definition

Leverage Ratios Maximum

+ References

No definition available.

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- Definition

Leverage Ratios, Step Up, Maximum

+ References

No definition available.

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- Definition

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

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- Definition

Weighted average interest rate of debt outstanding.

+ References

No definition available.

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- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.16)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 19, 20, 22
-Article 5

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- Definition

Date the credit facility terminates, in CCYY-MM-DD format.

+ 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 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Description of the interest rate for the amounts borrowed under the credit facility, including the terms and the method for determining the interest rate (for example, fixed or variable, LIBOR plus a percentage, increasing rate, timing of interest rate resets, remarketing provisions).

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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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- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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