Note 1 - Summary of Significant Accounting Policies (Details Textual)	12 Months Ended
	Dec. 31, 2019 USD ($) shares	Jan. 01, 2019 USD ($)	Dec. 31, 2018 USD ($) shares
Number Of Limited Partnerships In Housing Investments	10
Percentage of Subsidiaries Common Securities Owned by Parent Company	100.00%
Gross Loans Comprised of Commercial Mortgage Loans Percentage	48.30%
Residential Mortgages Properties Percentage	27.10%
Gross Loans Comprised of Commercial Loans Percentage	18.40%
Federal Home Loan Bank Stock	$ 18,090,000		$ 17,250,000
Minimum Stock Requirement on Outstanding Federal Home Loan Bank Borrowings Shares | shares	180,900		150,000
Maximum Loan Size Portfolio Stratification Homogenous Portfolio	$ 500,000
Variable Interest Entity, Primary Beneficiary, Number of Entities	9
Goodwill, Impairment Loss	$ 0
Number of Reportable Segments	1
Operating Lease, Liability, Total	$ 35,873,000		$ 0
Operating Lease, Right-of-Use Asset	$ 33,990,000		$ 0
Accounting Standards Update 2016-02 [Member]
Operating Lease, Liability, Total		$ 41,200,000
Operating Lease, Right-of-Use Asset		$ 40,600,000
California [Member]
Residential Mortgages Properties Percentage	54.00%