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Note 1 - Summary of Significant Accounting Policies (Details Textual) | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2017 USD ($) shares | Sep. 30, 2017 USD ($) | Jun. 30, 2017 USD ($) | Mar. 31, 2017 USD ($) | Dec. 31, 2016 USD ($) | Sep. 30, 2016 USD ($) | Jun. 30, 2016 USD ($) | Mar. 31, 2016 USD ($) | Dec. 31, 2017 USD ($) shares | Dec. 31, 2016 USD ($) | Dec. 31, 2015 USD ($) | Dec. 31, 2015 USD ($)
Number Of Limited Partnerships In Housing Investments | 8 |  |  |  |  |  |  |  | 8 |  |  |
Percentage of Subsidiaries Common Securities Owned by Parent Company | 100.00% |  |  |  |  |  |  |  | 100.00% |  |  |
Gross Loans Comprised of Commercial Mortgage Loans Percentage | 50.40% |  |  |  |  |  |  |  | 50.40% |  |  |
Residential Mortgages Properties Percentage | 23.80% |  |  |  |  |  |  |  | 23.80% |  |  |
Gross Loans Comprised of Commercial Loans Percentage | 19.10% |  |  |  |  |  |  |  | 19.10% |  |  |
Federal Home Loan Bank Stock | $ 23,085,000 |  |  |  | $ 17,250,000 |  |  |  | $ 23,085,000 | $ 17,250,000 |  |
Federal Home Loan Bank Stock Shares | shares | 230,850 |  |  |  |  |  |  |  | 230,850 |  |  |
Minimum Stock Requirement on Outstanding Federal Home Loan Bank Borrowings Shares | shares | 150,000 |  |  |  |  |  |  |  | 150,000 |  |  |
Maximum Loan Size Portfolio Stratification Homogenous Portfolio | $ 500,000 |  |  |  |  |  |  |  | $ 500,000 |  |  |
Number of Reportable Segments |  |  |  |  |  |  |  |  | 2 |  |  |
Number of Operating Segments |  |  |  |  |  |  |  |  | 1 |  |  |
Goodwill, Impairment Loss |  |  |  |  |  |  |  |  | $ 0 |  |  |
Income Tax Expense (Benefit) | $ 51,166,000 | $ 35,163,000 | $ 15,431,000 | $ 20,505,000 | $ 16,345,000 | $ 15,808,000 | $ 12,273,000 | $ 22,675,000 | 122,265,000 | $ 67,101,000 | $ 59,987,000 | $ 59,987,000
Accounting Standards Update 2016-09 [Member] |  |  |  |  |  |  |  |  |  |  |  |
Income Tax Expense (Benefit) |  |  |  |  |  |  |  |  | $ (3,800,000) |  |  |
California [Member] |  |  |  |  |  |  |  |  |  |  |  |
Residential Mortgages Properties Percentage | 61.00% |  |  |  |  |  |  |  | 61.00% |  |  |

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- Definition This represents the Federal Home Loan Bank (FHLB) shares owned by the Company as of the balance sheet date. FHLB stock represents an equity interest in a FHLB. It does not have a readily determinable fair value because its ownership is restricted and it lacks a market (liquidity). + References No definition available. + Details
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