a detailsRenderHint attribute is required on questionWithDetails. Iin the following example, the render hint makes both main question and details question radio buttons, however we want the details questions to be a picklist with only the main question being radio buttons.

        <!-- Tools and goods in transit -->
        <questionWithDetails title="Do you require cover for tools and goods in transit?" binding="/section[id='Trade']/attribute[id='TC_Required']" detailsTitle="Sum of tools insured?"
          detailsBinding="/section[id='Trade']/attribute[id='TC_Limit']" styleClass="required" renderHint="radio">
          <errorText error="invalid">Please select an option</errorText>
          <hintText>Tools cover provides insurance against loss or damage to your business tools and equipment.</hintText>
        </questionWithDetails>