Plan Asset and Target Asset Allocations (Detail)		Dec. 29, 2018	Dec. 30, 2017
Plan No. 1
Schedule Of Defined Benefit Plan Asset Allocation Targets [Line Items]
Percentage of Plan Assets at the Measurement Date		100.00%	100.00%
Plan No. 1 | Equity Securities
Schedule Of Defined Benefit Plan Asset Allocation Targets [Line Items]
Target Allocation 2019		0.00%
Percentage of Plan Assets at the Measurement Date		2.50%	38.60%
Plan No. 1 | Fixed Income Securities
Schedule Of Defined Benefit Plan Asset Allocation Targets [Line Items]
Percentage of Plan Assets at the Measurement Date		73.70%	27.10%
Plan No. 1 | Fixed Income Securities | Minimum
Schedule Of Defined Benefit Plan Asset Allocation Targets [Line Items]
Target Allocation 2019		90.00%
Plan No. 1 | Fixed Income Securities | Maximum
Schedule Of Defined Benefit Plan Asset Allocation Targets [Line Items]
Target Allocation 2019		100.00%
Plan No. 1 | Other Diversifying Strategies
Schedule Of Defined Benefit Plan Asset Allocation Targets [Line Items]
Target Allocation 2019	[1]	0.00%
Percentage of Plan Assets at the Measurement Date	[1]	15.00%	28.80%
Plan No. 1 | Short Term Investments And Cash
Schedule Of Defined Benefit Plan Asset Allocation Targets [Line Items]
Percentage of Plan Assets at the Measurement Date		8.80%	5.50%
Plan No. 1 | Short Term Investments And Cash | Minimum
Schedule Of Defined Benefit Plan Asset Allocation Targets [Line Items]
Target Allocation 2019		0.00%
Plan No. 1 | Short Term Investments And Cash | Maximum
Schedule Of Defined Benefit Plan Asset Allocation Targets [Line Items]
Target Allocation 2019		10.00%
Plan No. 2 | Equity Securities | Minimum
Schedule Of Defined Benefit Plan Asset Allocation Targets [Line Items]
Target Allocation 2019		0.00%
Plan No. 2 | Equity Securities | Maximum
Schedule Of Defined Benefit Plan Asset Allocation Targets [Line Items]
Target Allocation 2019		80.00%
Plan No. 2 | Fixed Income Securities | Minimum
Schedule Of Defined Benefit Plan Asset Allocation Targets [Line Items]
Target Allocation 2019		20.00%
Plan No. 2 | Fixed Income Securities | Maximum
Schedule Of Defined Benefit Plan Asset Allocation Targets [Line Items]
Target Allocation 2019		100.00%
Plan No. 2 | Short Term Investments And Cash | Minimum
Schedule Of Defined Benefit Plan Asset Allocation Targets [Line Items]
Target Allocation 2019		0.00%
Plan No. 2 | Short Term Investments And Cash | Maximum
Schedule Of Defined Benefit Plan Asset Allocation Targets [Line Items]
Target Allocation 2019		10.00%

[1] Includes absolute return funds, hedged equity funds, and guaranteed insurance contracts.