Stock-Based Compensation Plans (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
May 25, 2019	May 26, 2018	May 27, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in shares available for issuance	2,400,000
Shares available for grant	1,595,000	2,252,000
Stock options vesting period	4 years
Stock options termination period	10 years
Stock options exercise, intrinsic value	$ 5.2	$ 1.7	$ 1.1
Stock options vested, total fair value	5.4	$ 5.1	$ 3.6
Unrecognized compensation cost related to stock-based compensation	$ 8.3
Weighted average estimated value per share of employee stock options granted	$ 4.74	$ 3.61	$ 3.61
Share based compensation expense for restricted shares	$ 1.7	$ 1.4	$ 0.8
Restricted stock, shares granted	21,537	117,588	117,588
Share price	$ 15.56
Percentage of ownership threshold for minimum exercise price	10.00%
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in shares available for issuance	1,500,000
Shares of common stock made available for awards	5,900,000
Shares available for grant	221,000
Percentage of exercise price per share out of fair market value	85.00%
Common stock issued	358,000	339,000	359,000
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average period of cost to be recognized	1 year 7 months 2 days
Total unrecognized compensation cost	$ 2.9
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options vesting period	1 year
Percentage of exercise price per share out of fair market value	110.00%
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options vesting period	4 years

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Unrecognized cost of unvested share-based compensation awards.

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

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The noncash expense that represents the cost of restricted stock or unit distributed to employees as compensation.

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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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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Number of additional shares authorized for issuance under an established share-based compensation plan.

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The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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- Definition

The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Price of a single share of a number of saleable stocks of a company.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

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Purchase price of common stock expressed as a percentage of its fair value.

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Number of shares issued during the period as a result of an employee stock purchase plan.

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Total number of shares issued during the period, including shares forfeited, as a result of Restricted Stock Awards.

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