Condensed Consolidated Balance Sheets Unaudited (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current Assets:
Allowance for doubtful accounts	$ 9,046	$ 9,464
Class A Non-Voting
Shareholders' Investment:
Par or stated value per share (USD per share)	$ 1.00	$ 1.00
Shares authorized (shares)	50,000	50,000
Shares issued (shares)	30,723	30,847
Shares outstanding (shares)	30,723	30,847
Class B Voting
Shareholders' Investment:
Par or stated value per share (USD per share)	$ 1.00	$ 1.00
Shares authorized (shares)	50,000	50,000
Shares issued (shares)	22,429	22,510
Shares outstanding (shares)	22,429	22,510

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

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