In a read-only NumericField of a XamDataGrid I can set the Format easily with 

Format="###,###,##0.00;(###,###,##0.00)"

but I want to make this the default format so I'm trying to write a global default style. I think I need help understanding the correct target type. When I write a style like the one below the style is ignored. I have ensured this is the only default style for igDP:NumericField. 

xmlns:igDP="">infragistics.com/DataPresenter"

<Style TargetType="igDP:NumericField">
    <Setter Property="Format" Value="###,###,##0.00;(###,###,##0.00)"/>
</Style>

Thanks for your help.