Stock Compensation - Activity (Details) - $ / shares	3 Months Ended	9 Months Ended
Sep. 26, 2020	Sep. 28, 2019	Sep. 26, 2020	Sep. 28, 2019
Options Activity
Options granted (shares)	0	18,226	407,607	443,170
Options canceled (shares)	43,179	68,940	159,354	238,142
Options exercised (shares)	97,150	72,667	201,530	459,724
Options Weighted Average Exercise Price
Options granted, weighted average exercise price (usd per share)	$ 0	$ 20.88	$ 24.30	$ 20.94
Options canceled, weighted average exercise price (usd per share)	27.73	25.79	26.51	26.36
Options exercised, weighted average exercise price (usd per share)	$ 11.75	$ 12.25	$ 11.68	$ 9.44
Restricted stock units
Weighted Average Grant-Date Fair Value Per Share
Equity instruments granted (shares)	169,288	260,219	856,203	914,207
Equity instruments granted, weighted average exercise price (usd per share)	$ 16.48	$ 18.08	$ 19.59	$ 20.02
PSU's
Weighted Average Grant-Date Fair Value Per Share
Equity instruments granted (shares)	0	14,367	311,275	401,935
Equity instruments granted, weighted average exercise price (usd per share)	$ 0	$ 22.15	$ 25.50	$ 22.21

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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- Definition

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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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Number of share options (or share units) exercised during the current period.

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