No, you do not have to file a California state return if you have no other CA income.  Public Law 104-95 (P.L. 104-95)  prevents any state from taxing income from certain pensions and deferred compensation plans paid to individuals who are not residents or domiciliaries of that state.  If you are an Idaho resident, the income is taxable to Idaho only, regardless of where you lived when you earned the compensation  or who the payee is.