Note 22 - Income Taxes (Details Textual) - USD ($) $ in Millions	1 Months Ended	2 Months Ended	12 Months Ended
	Aug. 31, 2016	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Required Dividend Payout			90.00%
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent			21.00%
Federal Income Tax Benefit from AMT Credit Refunds				$ 3.7
Deferred Federal Income Tax Expense (Benefit)				(1.1)
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount					$ 1.6
Unrecognized Tax Benefits, Ending Balance		$ 2.4	$ 1.5	$ 2.4
Mexican Tax Authority [Member]
Tax Assessment Estimated Penalties Expense	$ 52.6
Tax Assessment, Estimated Penalties Expense, Amount Found to Be Improperly Assessed		16.1
Tax Assessment, Estimated Penalties Expense, Amount Found to Be Improperly Assessed, Reporting Entity’s Share		$ 12.8
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]
Effective Income Tax Rate Reconciliation, Real Estate Investment Trust, Amount			$ 1.5
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount					$ 0.3