Long-Term Debt and Financing Arrangements - Additional Information (Detail) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2015	Dec. 31, 2014
Standby Letters of Credit [Member]
Line Of Credit Facility [Line Items]
Outstanding letters of credit	$ 7.1
Letters of credit expiration, years	2016
Revolving Line of Credit Facility [Member] \| Bank Revolving Line of Credit [Member]
Line Of Credit Facility [Line Items]
Unused and available borrowings under bank revolving line of credit	$ 42.9	$ 43.9

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

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

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