Reconciliation Between Effective Income Tax Rate and Federal Statutory Income Tax Rate (Detail)		4 Months Ended	12 Months Ended
Dec. 31, 2017	Apr. 28, 2018	Apr. 28, 2018	Apr. 29, 2017	Apr. 30, 2016
Income Tax Rate Reconciliation [Line Items]
Federal statutory income tax rate	35.00%	21.00%	30.30%	35.00%	35.00%
State income taxes, net of federal income tax benefit			3.00%	10.00%	8.30%
Changes to unrecognized tax benefits			1.80%	(5.90%)	(111.30%)
Excess executive compensation			(0.10%)	0.30%	8.00%
Meals and entertainment disallowance			(0.20%)	0.50%	5.10%
Tax credits			0.60%		(76.30%)
Changes in valuation allowance			(26.70%)	(1.20%)	108.60%
Changes in deferred taxes and payables			(3.70%)	7.00%	(134.80%)
Amounts not deductible for tax			0.10%	1.90%
State law changes			1.50%	3.10%	4.70%
Impact of Tax Cuts and Jobs Act			4.10%
Goodwill impairment			(1.80%)
Other, net				2.20%	3.00%
Effective income tax rate			8.90%	52.90%	(149.70%)

Effective Income Tax Rate Reconciliation, Change In Deferred Tax And Payables

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Effective Income Tax Rate Reconciliation Nondeductible Expense Executive Compensation

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Effective Income Tax Rate Reconciliation, Nondeductible Expense, Goodwill Impairment Losses

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Percentage of reported income tax expense (benefit) in excess of (less than) expected income tax expense (benefit) computed by applying domestic federal statutory income tax rate to pretax income (loss) from continuing operations, attributable to increase (decrease) in income tax rate and transition tax on accumulated earnings of controlled foreign corporation deemed repatriated pursuant to Tax Cuts and Jobs Act of 2017.

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Income Tax Rate Reconciliation [Line Items]

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Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to changes in the valuation allowance for deferred tax assets.

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Percentage of the difference, between reported income tax expense (benefit) and the expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations, that is attributable to tax exempt income, equity in earnings (loss) of an unconsolidated subsidiary, minority interest income (expense), tax holiday, disposition of a business, disposition of an asset, repatriation of foreign earnings, repatriation of foreign earnings jobs creation act of 2004, change in enacted tax rate, prior year income taxes, change in deferred tax asset valuation allowance, and other adjustments.

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations applicable to state and local income tax expense (benefit), net of federal tax expense (benefit).

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to tax credits. Including, but not limited to, research credit, foreign tax credit, investment tax credit, and other tax credits.

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