How to bind data to to text box on drop down change in mvc 4

Question

How can i write dropdown change event in mvc

 

iam binding list of accounts in dropdown , when i select particular account i want to show amount of that account in textbox

 

where can i write dropdown change event in mvc

 

view

 

@Html.DropDownList("ddlAccount", Model.CustomerListModel, new { @style = "width:150px;height:22px;", @id = "ddlCustomer" }) 

 

Account Balance @Html.TextBox("AccountBalance", Model.TotalAmount, new { @class = "input-large" })

 

 

controller

 

var TotalAmount = db.Transaction_PaymentDetails.Select(m => m.Amount).Sum(); 

 i want to bind this TotalAmount  to text box on drop down change