Represents expected volatility rate period for share based payment award by share based payment.

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Fair value of non-vested equity-based payment instruments, excluding stock (or unit) options, vested.

+ References

No definition available.

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Represents historical volatility for fair value assumptions for share-based payment award by share based compensation.

+ References

No definition available.

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Percent of shares that may be issued in accordance with the plan as a proportion of outstanding awards.

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No definition available.

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Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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-Name Accounting Standards Codification
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Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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- Definition

The risk-free interest rate assumption that is used in valuing an option on its own shares.

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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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Gross number of share options (or share units) granted during the period.

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No definition available.

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Note 7 - Share-based Compensation (Details Textual) - USD ($)				3 Months Ended		9 Months Ended
	Mar. 25, 2020	Apr. 01, 2019	Feb. 25, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Payment Arrangement, Expense				$ 1,560,000	$ 829,000	$ 3,818,000	$ 2,179,000
Share-based Payment Arrangement, Option [Member]
Share-based Payment Arrangement, Expense				15,000	65,000	104,000	305,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value				28,600,000		28,600,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value				28,100,000		28,100,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value				2,200,000	1,700,000	$ 6,800,000	$ 5,200,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares)						0	0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term (Year)						3 years 9 months 18 days
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total				43,000		$ 43,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)						1 year
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares)						0
Performance Shares [Member] \| Management Performance Bonus Plan 2017 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value				19,700,000		$ 19,700,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value				$ 0	$ 2,300,000	$ 239,000	$ 2,300,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares)				0	0	0	0
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)						1 year 2 months 12 days
Restricted Stock [Member]
Share-based Payment Arrangement, Expense				$ 754,000	$ 303,000	$ 1,600,000	$ 826,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total				10,000,000.0		$ 10,000,000.0
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)						3 years 3 months 18 days
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Fair Value				4,200,000	802,000,000,000	$ 7,400,000	4,000,000.0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value				1,600,000	368,000	$ 2,900,000	1,600,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)						448,267
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share)						$ 15.78
Restricted Stock [Member] \| Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)	34,154					34,154
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share)	$ 9.18					$ 9.18
Performance-based Restricted Stock [Member]
Share-based Payment Arrangement, Expense				191,000		$ 569,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total				191,000		$ 191,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)						3 months 18 days
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)	82,805					82,805
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share)	$ 9.18					$ 9.18
Performance-based Restricted Stock [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Percentage of Awards	0.00%
Performance-based Restricted Stock [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Percentage of Awards	125.00%
Market-based Restricted Stock [Member]
Share-based Payment Arrangement, Expense				600,000	$ 461,000	$ 1,500,000	$ 1,000,000.0
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total				$ 1,300,000		$ 1,300,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)						10 months 24 days
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)	109,140	29,604	94,247
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number, Ending Balance	78.00%	69.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate	0.00%	0.00%
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	0.30%	2.50%
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period (Year)	2 years	2 years
Market-based Restricted Stock [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Percentage of Awards	0.00%	0.00%
Market-based Restricted Stock [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Percentage of Awards	200.00%	200.00%