Note 21 - Income Taxes (Details Textual) - USD ($) $ in Millions	1 Months Ended	2 Months Ended	12 Months Ended
	Aug. 31, 2016	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Required Dividend Payout		90.00%	90.00%
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent			21.00%		35.00%
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability					$ 1.1
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount				$ 1.6
Federal Income Tax Benefit from AMT Credit Refunds			$ 3.7
Deferred Federal Income Tax Expense (Benefit)			(1.1)
Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax		$ 3.5	$ 3.5
Open Tax Year			2010 2011 2012 2013 2014 2015 2016 2017 2018
Mexican Tax Authority [Member]
Tax Assessment Estimated Penalties Expense	$ 52.6
Tax Assessment, Estimated Penalties Expense, Amount Found to Be Improperly Assessed, Reporting Entity’s Share		14.7
Tax Assessment, Estimated Penalties Expense, Amount Found to Be Improperly Assessed		$ 17.9
Mexican Tax Authority [Member] | Tax Year 2010 [Member]
Income Tax Examination, Year under Examination	2010
Tax Assessment Estimated Tax Expense	$ 33.7
Tax Assessment Estimated Interest Expense	16.5
Tax Assessment Estimated Penalties Expense	$ 11.4
State and Local Jurisdiction [Member]
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount				$ 0.3