MasterDetailPage navigation history

I have created a MasterDetailPage and each time I select an item in my MenuPage the content is correctly displayed.

However, when I press the physical back button of my smartphone my application automatically close.

I tried to pass my NavigationPage to Navigation.PushAsync() but that throws an exception as the page already as a parent.

This is my current code which is working, but no navigation history:

MainActivity.cs:

protected override void OnCreate(Bundle bundle)
{
    base.OnCreate(bundle);
    Xamarin.Forms.Forms.Init(this, bundle);
    SetPage(App.GetMainPage());
}

App.cs:

public class App
    {
        public static Page GetMainPage()
        {
            return new RootMasterDetailPage();
        }
    }

RootMasterDetailPage.cs:

class RootMasterDetailPage : MasterDetailPage
{
    OptionItem previousItem;

    public RootMasterDetailPage()
    {
        var masterPage = new MenuPage();
        masterPage.Menu.ItemSelected += (sender, e) => NavigateTo(e.SelectedItem as OptionItem);

        Master = masterPage;

        NavigateTo(masterPage.Menu.ItemsSource.Cast<OptionItem>().First());   
    }

    void NavigateTo(OptionItem option)
    {
        if (previousItem != null)
            previousItem.Selected = false;

        option.Selected = true;
        previousItem = option;

        var displayPage = PageForOption(option);

        Detail = new NavigationPage(displayPage); ;

        IsPresented = false;
    }

    Page PageForOption(OptionItem option)
    {
        if (option.Title == Constants.PageName.Home)
            return new HomePage();

        if (option.Title == Constants.PageName.Faq)
            return new FaqPage();

        if (option.Title == Constants.PageName.Contact)
            return new ContactPage();

        throw new InvalidOperationException();
    }
}

How can I handle the navigation history to allow my user to go back to previous detailled pages by using the smartphone back button?