2.4.0.8028 - Disclosure - Significant Subsidiaries (Details Textual)truefalsefalse1false falsefalseContext_FYE_31-Mar-2013http://www.sec.gov/CIK0000911568duration2012-04-01T00:00:002013-03-31T00:00:001false 4bftcviii_EquityMethodInvestmentOwnershipPercentageCriteriabftcviii_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse0020%falsefalsefalsexbrli:stringItemTypestringDescription about the percentage criteria of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.No definition available.false0Equity Method Investment, Ownership Percentage CriteriafalseSignificant Subsidiaries (Details Textual)UnKnownUnKnownUnKnownUnKnowntruefalsefalseSheethttp://www.bostonfinancial.com/role/SignificantSubsidiariesDetailsTextual11