Condensed Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015	[1]
Current Assets:
Allowance for doubtful accounts	$ 14,174	$ 13,133
Common Class A
Shareholders' Investment:
Par or stated value per share (usd per share)	$ 1	$ 1
Shares authorized (shares)	50,000,000	50,000,000
Shares issued (shares)	30,952,000	30,537,000
Shares outstanding (shares)	30,952,000	30,537,000
Common Class B
Shareholders' Investment:
Par or stated value per share (usd per share)	$ 1	$ 1
Shares authorized (shares)	50,000,000	50,000,000
Shares issued (shares)	24,690,000	24,690,000
Shares outstanding (shares)	24,690,000	24,690,000

[1] Derived from the audited Consolidated Balance Sheet.