Long Term Debt and Capital Lease Obligations - Additional Information (Detail) (USD $) In Millions, unless otherwise specified			1 Months Ended
Sep. 30, 2013	Dec. 31, 2012	Nov. 27, 2012 6.0% Senior Notes Due 2022	Sep. 30, 2013 6.0% Senior Notes Due 2022
Convertible Promissory Notes And Warrants [Line Items]
Debt maturity period			2022	2022
Aggregate principal amount senior notes issued	$ 717.0	$ 723.0	$ 300.0
Percentage of principal amount of notes issued			100.00%
Date of exchange offer of all outstanding 2022 Notes			Jul. 26, 2013

Amount of long-term debt before deduction of unamortized discount or premium. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, with initial maturities beyond one year or the normal operating cycle, if longer.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 20

-Article 5

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 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 210.5-02.22)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 9

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