Serialize object to XmlDocument

In order to return useful information in SoapException.Detail for an asmx web service, I took an idea from WCF and created a fault class to contain said useful information. That fault object is then serialised to the required XmlNode of a thrown SoapException.

I'm wondering whether I have the best code to create the XmlDocument - here is my take on it:

var xmlDocument = new XmlDocument();
var serializer = new XmlSerializer(typeof(T));
using (var stream = new MemoryStream())
{
    serializer.Serialize(stream, theObjectContainingUsefulInformation);
    stream.Flush();
    stream.Seek(0, SeekOrigin.Begin);

    xmlDocument.Load(stream);
}

Is there a better way of doing this?

UPDATE: I actually ended up doing the following, because unless you wrap the XML in a <detail> xml element, you get a SoapHeaderException at the client end:

var serialiseToDocument = new XmlDocument();
var serializer = new XmlSerializer(typeof(T));
using (var stream = new MemoryStream())
{
    serializer.Serialize(stream, e.ExceptionContext);
    stream.Flush();
    stream.Seek(0, SeekOrigin.Begin);

    serialiseToDocument.Load(stream);
}

// Remove the xml declaration
serialiseToDocument.RemoveChild(serialiseToDocument.FirstChild);

// Memorise the node we want
var serialisedNode = serialiseToDocument.FirstChild;

// and wrap it in a <detail> element
var rootNode = serialiseToDocument.CreateNode(XmlNodeType.Element, "detail", "");
rootNode.AppendChild(serialisedNode);

UPDATE 2: Given John Saunders excellent answer, I've now started using the following:

private static void SerialiseFaultDetail()
{
    var fault = new ServiceFault
                    {
                        Message = "Exception occurred",
                        ErrorCode = 1010
                    };