CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 27, 2020	Dec. 29, 2019
Accounts receivable, allowances	$ 13,797	$ 14,358
Common stock, par value (USD per share)	$ 0.10	$ 0.10
Class A Common Stock
Authorized shares (in shares)	300,000,000	300,000,000
Issued shares (in shares)	175,308,672	174,242,668
Treasury shares (in shares)	8,870,801	8,870,801
Class B Common Stock
Authorized shares (in shares)	781,724	803,404
Issued shares (in shares)	781,724	803,404
Treasury shares (in shares)	0	0

Amount of allowance for credit loss on accounts receivable, classified as current.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Topic 210
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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