Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Number of options outstanding, including both vested and non-vested options.

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Number of shares (or other type of equity) issued during the period as a result of any equity-based compensation plan other than an employee stock ownership plan (ESOP), net of any shares forfeited. Shares issued could result from the issuance of restricted stock, the exercise of stock options, stock issued under employee stock purchase plans, and/or other employee benefit plans.

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Stock-Based Compensation Plans - 2007 Stock Incentive Plan (Details) - shares			12 Months Ended
	May 24, 2018	May 24, 2007	Dec. 31, 2018
Stock-based compensation plans
Restricted stock, forfeited, and returned to pool			176,644
Number of shares available			890,730
The 2007 plan
Stock-based compensation plans
Number of shares authorized		2,800,000
Restricted Stock \| The 2007 plan
Stock-based compensation plans
Stock options outstanding (in shares)			0
Number of shares awarded			2,885,914
Restricted Stock \| 2018 Plan
Stock-based compensation plans
Number of shares authorized	800,000
Minimum \| Restricted Stock \| The 2007 plan
Stock-based compensation plans
Vesting period		1 year
Minimum \| Restricted Stock \| 2018 Plan
Stock-based compensation plans
Vesting period	1 year
Maximum \| Restricted Stock \| The 2007 plan
Stock-based compensation plans
Vesting period		4 years
Maximum \| Restricted Stock \| 2018 Plan
Stock-based compensation plans
Vesting period	4 years