 | us-gaap:DebtSecuritiesRealizedGainLoss | summation-item | http://fasb.org/us-gaap/role/statement/StatementOfIncome |
 | us-gaap:NetRealizedOrUnrealizedGainLossOnTradingSecuritiesAbstract | parent-child | http://fasb.org/us-gaap/role/disclosure/InvestmentsDebtAndEquitySecuritiesTmp04 |
 | us-gaap:DebtSecuritiesTradingGainLoss | summation-item | http://fasb.org/us-gaap/role/disclosure/InvestmentsDebtAndEquitySecuritiesTmp04 |
 | us-gaap:DebtSecuritiesRealizedGainLossAbstract | parent-child | http://fasb.org/us-gaap/role/disclosure/InvestmentsDebtAndEquitySecurities |
 | us-gaap:DebtSecuritiesRealizedGainLossExcludingOtherThanTemporaryImpairmentAbstract | parent-child | http://fasb.org/us-gaap/role/disclosure/InvestmentsDebtAndEquitySecurities |
 | us-gaap:TradingSecuritiesRealizedGainLossAbstract | parent-child | http://fasb.org/us-gaap/role/disclosure/InvestmentsDebtAndEquitySecurities |
 | us-gaap:DebtSecuritiesTradingGainLoss | summation-item | http://fasb.org/us-gaap/role/disclosure/InvestmentsDebtAndEquitySecurities |
 | us-gaap:DebtSecuritiesRealizedGainLossExcludingOtherThanTemporaryImpairmentAbstract | domain-member | http://fasb.org/us-gaap/role/disclosure/InvestmentsDebtAndEquitySecuritiesScheduleOfGainLossOnInvestmentsTable |
 | us-gaap:TradingSecuritiesRealizedGainLossAbstract | domain-member | http://fasb.org/us-gaap/role/disclosure/InvestmentsDebtAndEquitySecuritiesScheduleOfTradingSecuritiesAndOtherTradingAssetsTable |
 | us-gaap:DebtSecuritiesRealizedGainLossExcludingOtherThanTemporaryImpairment | summation-item | http://fasb.org/us-gaap/role/disclosure/FinancialInstrumentsFairValueDisclosures |