使用动态类型调用泛型扩展方法

我正在尝试执行一个返回类型T的对象的扩展方法，但我正在尝试基于Header/Detail动态泛型类型动态T类型。

这可能有点啰嗦…

using System;
using System.Collections.Generic;
namespace Blah
{
    public interface IHeader
    {
        string Name { get; set; }
        IDetail Detail { get; set; }
    }
    public interface IDetail
    {
        //Nothing the 'Real' implementation of this 
        //interface will have it's own properties.
    }
    public class GenericHeader : IHeader
    {
        public string Name { get; set; }
        public IDetail Detail { get; set; }
    }
    public class RealHeader : GenericHeader
    {
        public new RealDetail Detail
        {
            get { return (RealDetail) base.Detail; }
            set { base.Detail = value; }
        }
    }
    public class RealDetail : IDetail
    {
        public string ThisImportantOnlyToRealDetail { get; set; }
    }
    public static class ExtensionHelpers
    {
        public static T ToObject<T>(this IDictionary<string, string> reader) where T : new()
        {
            //This maps the dictionary to Key Value Pairs of the Object's properties
            //it then will return a object filled with the values
            return new T();
        }
    }
    public class MyRepo<THeader> where THeader : class, IHeader, new()
    {
        public THeader GetById(int ID)
        {
            THeader returnHeader = new THeader();
            //Process to fill Header
            var dictDetail = new Dictionary<string, string>();
            //Process to fill Detail Dictionary
            //Use extension method to create an Object 
            //based on Key Value Pairs from Dictionary
            // !!!!!!!!!!!!!!!! This Is The Problem !!!!!!!!!!!!!!!!
            // Can't use typeof for returnHeader.Detail, reflection?
            returnHeader.Detail = dictDetail.ToObject<typeof(returnHeader.Detail)>();
            return returnHeader;
        }
    }
    public class Worker
    {
        public void DoWork()
        {
            var myRealRepo = new MyRepo<RealHeader>();
            var myRealHeader = myRealRepo.GetById(123);
            Console.WriteLine(myRealHeader.Detail.ThisImportantOnlyToRealDetail);
        }
    }
}

typeof(ExtensionHelpers)
    .GetMethod("ToObject", BindingFlags.Static | BindingFlags.Public)
    .MakeGenericMethod(returnHeader.Detail.GetType())
    .Invoke(null, new object[] { dictDetail });