// Get a BoundingBoxXYZ instance from Revit
BoundingBoxXYZ box = document.ActiveView.CropBox;
if (null == box)
{
    throw new Exception("No BoundingBoxXYZ instance found.");
}

// Create a new view section.
ElementId DetailViewId = ElementId.InvalidElementId;
IList<Element> elems = new FilteredElementCollector(document).OfClass(typeof(ViewFamilyType)).ToElements();
foreach (Element e in elems)
{
    ViewFamilyType v = e as ViewFamilyType;

    if (v != null && v.ViewFamily == ViewFamily.Detail)
    {
        DetailViewId = e.Id;
        break;
    }
}
ViewSection viewSection = ViewSection.CreateDetail(document, DetailViewId, box);

' Get a BoundingBoxXYZ instance from Revit
Dim box As BoundingBoxXYZ = document.ActiveView.CropBox
If box Is Nothing Then
    Throw New Exception("No BoundingBoxXYZ instance found.")
End If

' Create a new view section.
Dim DetailViewId As ElementId = ElementId.InvalidElementId
Dim elems As IList(Of Element) = New FilteredElementCollector(document).OfClass(GetType(ViewFamilyType)).ToElements()
For Each e As Element In elems
    Dim v As ViewFamilyType = TryCast(e, ViewFamilyType)

    If v IsNot Nothing AndAlso v.ViewFamily = ViewFamily.Detail Then
        DetailViewId = e.Id
        Exit For
    End If
Next
Dim viewSection__1 As ViewSection = ViewSection.CreateDetail(document, DetailViewId, box)