Fee Footnote Performance Heading Share Class [Axis] Performance Measure [Axis] Prospectus [Table] All Classes Average Annual Return, Column Name Series [Axis] All Series All Prospectus Prospectus [Axis] Creation Date Effective Date Period End Date Trading Symbol Expense Example, 1 YEAR Expense Example, No Redemption, 1 YEAR Expense Example, 3 YEARS Expense Example, No Redemption, 3 YEARS Expense Example, 5 YEARS Expense Example, No Redemption, 5 YEARS Expense Example, 10 YEARS Expense Example, No Redemption, 10 YEARS Expense Example, Note 1 Year 1 Year 3 Years 3 Years 5 Years 5 Years 10 Years 10 Years CIK Registrant Name Document Type Amendment Am.Description Prospectus Date California Tax-Free Income Fund California Insured Intermediate Fund California Tax-Free Money Market Fund S&P 500 Index Fund S&P MidCap Index Fund S&P SmallCap Index Fund Shelton Core Value Fund Nasdaq-100 Index Fund European Growth & Income Fund U.S. Government Securities Fund Short-Term U.S Government Bond Fund The United States Treasury Trust S&P 500 Index Fund - Class K S&P MidCap Index Fund - Class K S&P SmallCap Index Fund - Class K Shelton Core Value Fund - Class K Nasdaq-100 Index Fund - Class K European Growth & Income Fund - Class K U.S. Government Securities Fund - Class K Short-Term U.S Government Bond Fund - Class K The United States Treasury Trust - Class K Shelton Core Value Fund - Class A U.S. Government Securities Fund - Class A Direct Shares C000031070Member Direct Shares C000031071Member Direct Shares C000031072Member Direct Shares C000044029Member Direct Shares C000044031Member Direct Shares C000044033Member Direct Shares C000044035Member Direct Shares C000044038Member Direct Shares C000044039Member Direct Shares C000044041Member Direct Shares C000044043Member Direct Shares C000044045Member K Shares C000044030Member K Shares C000044032Member K Shares C000044034Member K Shares C000044036Member K Shares C000044037Member K Shares C000044040Member K Shares C000044042Member K Shares C000044044Member K Shares C000044046Member Class A C000088543Member Class A C000088544Member Class A C000088545Member Class A C000088546Member Risk/Return: Risk/Return Investment objective: Investment objective Secondary objectives Fees and expenses of the fund: Fees and expenses of the fund, narrative Shareholder fees, caption Shareholder fees, table Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) Maximum Cumulative Sales Charge / Other Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of purchase price) Maximum Deferred Sales Charge (Load) (as a percentage of purchase price) Maximum deferred sales charge (as a percentage of the amount redeemed) Maximum Sales Charge (Load) Imposed on Reinvested Dividends (and other Distributions) (as a percentage of purchase price) Redemption Fee (as a percentage of amount redeemed, if applicable) Redemption Fee (as a percentage of amount redeemed, if applicable) Redemption Fee (as a percentage of amount redeemed, if applicable) Wire Redemption Fees on Redemptions less than $10,000 Exchange Fee (as a percentage of net assets) Exchange Fee Maximum Account Fee (as a percentage of net assets) Maximum Account Fee (applies to accounts with balances of less than $10,000) Sales and redemption charges Annual fund operating expenses, heading Annual fund operating expenses, table Management fees Distribution (12b-1) fees Distribution or similar (non 12b-1) Fees (as a percentage of net assets) Other Expenses, Component 1 (as a percentage of net assets) Other Expenses, Component 2 (as a percentage of net assets) Other Expenses, Component 3 (as a percentage of net assets) Other expenses Acquired Fund Fees and Expenses (as a percentage of net assets) Total annual operating expenses Fee Waiver and/or Expense Reimbursement Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement Portfolio turnover, heading Portfolio turnover, narrative Portfolio Turnover Rate Expense Footnotes Deferred Charges, Narrative Range of Exchange Fees, Narrative Expense Breakpoint Discounts Expense Breakpoint, Minimum Investment Required Expense Exchange Traded Fund Commissions Expenses Represent Both Master and Feeder Expenses Explanation of Nonrecurring Account Fee Other Expenses, New Fund, Based on Estimates Acquired Fund Fees and Expenses, Based on Estimates Expenses Other Expenses Had Extraordinary Expenses Been Included Expenses Restated to Reflect Current Expenses Not Correlated to Ratio Due to Acquired Fund Fees Example, heading Expense Example, with Redemption, heading Expense Example, Narrative Expense Example, with Redemption, Caption Expense Example, with Redemption, table Expense Example, Column Name Expense Example, No Redemption, Narrative Expense Example, No Redemption, Caption Expense Example, No Redemption, table Expense Example, No Redemption, Column Name Expense Example Footnotes Expense Example Closing Strategy, Heading Strategy, Narrative Portfolio Concentration Risk, Heading Risk, Narrative Risk Footnotes Risk Closing May Lose Money Date Of Termination Nondiversified Money Market Fund Not Insured Depository Institution Risk Caption Risk Column Name Risk Bar Chart and Performance Table, Heading Performance, Narrative Performance, Information Illustrates Variability of Returns Performance, One Year or Less Performance, Additional Market Index Performance, Availability by Phone Performance, Availability at Web Site Address Performance, Past Does Not Indicate Future Bar Chart, Heading Bar Chart, Narrative Bar Chart, Does Not Reflect Sales Loads Bar Chart Annual Return, Caption Annual Return, Inception Date 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 Bar Chart, Footnotes Bar Chart, Closing Bar Chart, Reason Selected Class Different from Immediately Preceding Period Bar Chart, Returns for Class Not Offered in Prospectus Year to Date Return, Label Year to Date Return, Date Year to Date Return Highest Quarterly Return, Label Highest Quarterly Return Date Highest Quarterly Return Lowest Quarterly Return, Label Lowest Quarterly Return Date Lowest Quarterly Return Performance Table: Performance Table Narrative Average Annual Return Caption Performance Table 1 Year 5 Years 10 Years Since Inception Inception Date Before taxes - Return After Taxes on Distributions - Return After Taxes on Distributions and Sale of Fund Shares Market Index Performance Barclays Municipal Bond Index bmbidMember Barclays 5 year Municipal Bond Index b5mbidMember S&P 500 Composite Stock Price Index S&P 500 Composite Stock Price Index S&P 500 Composite Stock Price Index S&P 500 Composite Stock Price Index S&P 500 Composite Stock Price Index snpcspidMember snpcspiedMember snpcspikMember snpcspiekMember index2Member S&P MidCap 400 Index S&P MidCap 400 Index snp400dMember snp400kMember S&P SmallCap 600 Index S&P SmallCap 600 Index snp600dMember snp600kMember S&P Citigroup Value Index S&P Citigroup Value Index S&P Citigroup Value Index snpcitidMember snpcitikMember index1Member Nasdaq-100 Index Nasdaq-100 Index n100dMember n100kMember Dow Jones European STOXX 50 Index Dow Jones European STOXX 50 Index dje50dMember dje50kMember Barclays GNMA Index Barclays GNMA Index Barclays GNMA Index bgnmadMember bgnmakMember index3Member Barclays Treasury Index Barclays Treasury Index btidMember btikMember Barclays 1-3 yr. Treasury Index Barclays 1-3 yr. Treasury Index b13tidMember b13tikMember Performance Table Footnotes, Reason Performance Information for Class Different from Immediately Preceding Period Performance Table Footnotes Performance Table Closing Performance Table Does Reflect Sales Loads Performance Table Market Index Changed Index No Deduction for Fees, Expenses, Taxes Performance Table Uses Highest Federal Rate Performance Table Not Relevant to Tax Deferred One Class of After-Tax Shown Performance Table Explains why after Tax Higher Money Market, Seven Day Yield Caption Money Market, Seven Day Yield Column Name 7-Day Yield Phone 7-Day Yield 7-Day Tax Equivalent Yield Thirty Day Yield Caption Thirty Day Yield Column Name 30-Day Yield Phone 30-Day Yield 30-Day Tax Equivalent Yield Risk/Return Detail Table Text Block