Pension Plans (Summary Of Amounts Included In Accumulated Other Comprehensive Income (Loss)) (Detail) (USD $) In Millions, unless otherwise specified	Dec. 29, 2012	Dec. 31, 2011
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Net gain (loss), net of tax of $147.1 million and $155.6 million, respectively	$ (260.4)	$ (268.0)
Prior service credit (cost), net of tax of $2.5 million and $1.9 million, respectively	4.0	(3.0)
Amounts included in accumulated other comprehensive income (loss)	$ (256.4)	$ (271.0)

Pension and other postretirement benefit plans, accumulated other comprehensive income (loss), net prior service cost (credit), net of tax

No definition available.

Name:	sna_PensionAndOtherPostretirementBenefitPlansAccumulatedOtherComprehensiveIncomeLossNetPriorServiceCostCreditNetOfTax
Namespace Prefix:	sna_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant