How to use RunOnUIThread() in Xamarin Android

I would like to run this statement after getting result into OStateUserId object.

details.Text = OStateUserID.name + "\n" + OStateUserID.population);

bStateuserID.Click +=  async delegate 
{
    details.Text=" ";
    Guid x = new Guid("33F8A8D5-0DF2-47A0-9C79-002351A95F88");
    state OStateUserID =(state) await obj.GetStateByUserId(x.ToString());
    details.Text = OStateUserID.name + "\n" + OStateUserID.population);
};

GetStateByUserId() method returns an object of class State.

It runs asynchronously. After completing operation, I'd like to assign the name and population to the TextView details.

How can i use RunOnUIThread() in this case?