Debt - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	1 Months Ended
Dec. 31, 2010	Sep. 30, 2011
Debt Instrument [Line Items]
2010 Credit Agreement, term loan and revolving credit facility maturity	5 years
2010 Credit Agreement, expansion feature by which the term loan and revolving credit facility may be increased	$ 150.0
2010 Credit Agreement, interest rate description	either (i) the greatest of: the administrative agent’s prime rate; the average rate on overnight federal funds plus 1/2 of 1%; and the eurodollar rate (adjusted for statutory reserves) plus 1%, in each case plus a margin equal to between 0.50% and 1.25% depending on the Company’s leverage ratio as of the end of the four consecutive fiscal quarters most recently ended, or (ii) the eurodollar rate (adjusted for statutory reserves) plus a margin equal to between 1.50% and 2.25%
Average rate on overnight federal funds plus 1/2 of	1.00%
Eurodollar rate plus	1.00%
Notional fixed-for-floating interest rate swap contract		200.0
Base fixed rate		2.26%
Interest rate swap fair value		10.3
Outstanding letters of credit and guarantees	5.3	4.8
Term Loan
Debt Instrument [Line Items]
2010 Credit Agreement, maximum borrowing capacity	200.0
Term loan repayment	19 consecutive quarterly installments
Debt instrument, final payment due	Dec. 22, 2015
Revolver
Debt Instrument [Line Items]
2010 Credit Agreement, maximum borrowing capacity	400.0
Debt instrument, final payment due	Dec. 22, 2015
Revolver \| Letter of Credit
Debt Instrument [Line Items]
2010 Credit Agreement, maximum borrowing capacity	$ 40.0
Federal Funds Rate \| Euro Dollar Rate
Debt Instrument [Line Items]
Plus minimum margin	0.50%
Plus maximum margin	1.25%
Euro Dollar Rate
Debt Instrument [Line Items]
Plus minimum margin	1.50%
Plus maximum margin	2.25%

Debt Instrument Interest Additional Interest Above Eurodollar Rate

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- Definition

Debt Instrument Interest Additional Interest Above Federal Fund Rate

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- Definition

Debt Instruments, Maturity Duration

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- Definition

Line of Credit Facility, Additional Borrowing Capacity

+ Details

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- Definition

Maximum Applicable Margin Rate

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- Definition

Minimum Applicable Margin Rate

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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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- Definition

Date when the debt instrument is scheduled to be fully repaid, which may be presented in a variety of ways (year, month and year, day, month and year, quarter, etc.).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 129

-Paragraph 2, 4

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

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-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef

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-Topic 210

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-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(2))

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- Definition

Fixed interest rate related to the interest rate derivative.

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- Definition

Fair value of all derivatives designated as interest rate fair value hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 17

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 45

-Paragraph 5

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- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

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- Definition

Description of the frequency of periodic payments, which may be presented in a variety of ways (for example, monthly, quarterly, annually).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 129

-Paragraph 2, 4

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

Reference 3: 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).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 129

-Paragraph 2, 4

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

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-Subparagraph (SX 210.5-02.19(b),22(b))

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 129

-Paragraph 2, 4

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

Reference 3: 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

Aggregate notional amount of interest rate derivatives, which relates to the currency amount specified in the interest rate derivative instruments.

+ 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=6935481&loc=SL5580258-113959

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-Publisher FASB

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-Glossary Notional Amount

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-Subparagraph (d)

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