Note 17 - Subsequent Events (Details Textual) - USD ($) $ in Thousands			12 Months Ended
	Mar. 02, 2021	Jan. 06, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jan. 28, 2021	Jan. 25, 2021
Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property			$ 7,677	$ 2,829	$ (298)
Insurance Policy Primary Occurence Limit			9,000
Insurance Policy Excess Coverage			$ 1,000
Subsequent Event [Member]
Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property		$ 1,000
Insurance Policy Primary Occurence Limit						$ 7,000
Insurance Policy Excess Coverage						$ 3,000
Subsequent Event [Member] | Common Class A [Member]
Stock Repurchase Program, Authorized Amount							$ 40,000
Treasury Stock, Shares, Acquired (in shares)	362,988