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Disclosure - Note 16 - Stock-based Compensation - Summary of Awards Pursuant to Stock Option Plans (Details) Sheet http://www.royalbusinessbankusa.com/20230930/role/statement-note-16-stockbased-compensation-summary-of-awards-pursuant-to-stock-option-plans-details Note 16 - Stock-based Compensation - Summary of Awards Pursuant to Stock Option Plans (Details) Details 86 false false R87.htm 995531 - Disclosure - Note 16 - Stock-based Compensation - Restricted Stock Activity (Details) Sheet http://www.royalbusinessbankusa.com/20230930/role/statement-note-16-stockbased-compensation-restricted-stock-activity-details Note 16 - Stock-based Compensation - Restricted Stock Activity (Details) Details 87 false false R88.htm 995532 - Disclosure - Note 17 - Regulatory Matters (Details Textual) Sheet http://www.royalbusinessbankusa.com/20230930/role/statement-note-17-regulatory-matters-details-textual Note 17 - Regulatory Matters (Details Textual) Details http://www.royalbusinessbankusa.com/20230930/role/statement-note-17-regulatory-matters-tables 88 false false R89.htm 995533 - Disclosure - Note 17 - Regulatory Matters - Summary of Company and Bank Continue to Exceed Regulatory Capital Minimum Requirements and Bank Continues to Exceed Well Capitalized Standards (Details) Sheet http://www.royalbusinessbankusa.com/20230930/role/statement-note-17-regulatory-matters-summary-of-company-and-bank-continue-to-exceed-regulatory-capital-minimum-requirements-and-bank-continues-to-exceed-well-capitalized-standards-details Note 17 - Regulatory Matters - Summary of Company and Bank Continue to Exceed Regulatory Capital Minimum Requirements and Bank Continues to Exceed Well Capitalized Standards (Details) Details 89 false false R90.htm 995534 - Disclosure - Note 18 - Fair Value Measurements and Fair Value of Financial Instruments (Details Textual) Sheet http://www.royalbusinessbankusa.com/20230930/role/statement-note-18-fair-value-measurements-and-fair-value-of-financial-instruments-details-textual Note 18 - Fair Value Measurements and Fair Value of Financial Instruments (Details Textual) Details http://www.royalbusinessbankusa.com/20230930/role/statement-note-18-fair-value-measurements-and-fair-value-of-financial-instruments-tables 90 false false R91.htm 995535 - 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