Amount of employer's best estimate of contributions expected to be paid to the plan during the next fiscal year beginning after the date of the latest statement of financial position.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (g)

-URI http://asc.fasb.org/extlink&oid=28361610&loc=d3e1928-114920

Name:	us-gaap_DefinedBenefitPlansEstimatedFutureEmployerContributionsInNextFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Retirement Benefits - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended	12 Months Ended		12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012 Pension Plans	Jun. 30, 2013 Pension Plans	Dec. 31, 2012 Other Postretirement Benefit Plans	Jun. 30, 2013 Other Postretirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Expected contribution for next fiscal year		$ 7.0		$ 0.9
Actual contributions			3.4		0.5
Anticipated additional contribution for pension plans and other postretirement benefit plans in 2013	$ 4.0