Condensed Consolidated Statements of Stockholders' Equity (Unaudited) (Parentheticals) - USD ($) $ in Thousands	3 Months Ended
Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018
Common Class A [Member]
Dividends declared (in dollars per share)	$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.06
Common Class B [Member]
Dividends declared (in dollars per share)	$ 0.07	$ 0.07	$ 0.07	$ 0.07	$ 0.07	$ 0.07
Currency translation adjustment, tax	$ (13)	$ (16)	$ 17	$ 1	$ (37)	$ 25
Change in unfunded SERP liability, tax	(11)	$ (11)	$ (11)	(25)	$ (25)	(25)
Unrealized loss on marketable securities arising during the period, tax	$ 0			$ (3)		$ 20

Aggregate dividends declared during the period for each share of common stock outstanding.

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Amount of tax expense (benefit), after reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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