c# how to get to idle from walk

i have a basic move script and key press on the w witcn is move forward i want it to play the walk animation witch i got working but when the player stops i want it to return to the idle animation this is the line of code i am using for movement

private void MovePlayer(){

     /***** CAN BE MODIFIED *****/
     // 
     if (Input.GetKey(KeyCode.W) || Input.GetKey(KeyCode.UpArrow)) {
         transform.Translate(new Vector3(0,0,1) * speed);
         animation.Play("Walk");
     } else if (Input.GetKey(KeyCode.S) || Input.GetKey(KeyCode.DownArrow)) {
         transform.Translate(new Vector3(0,0,-1) * speed);
     }

     if (Input.GetKey(KeyCode.A) || Input.GetKey(KeyCode.LeftArrow)) {
         transform.Rotate(new Vector3(0,-1,0) * 2);
     } else if (Input.GetKey(KeyCode.D) || Input.GetKey(KeyCode.RightArrow)) {
         transform.Rotate(new Vector3(0,1,0) * 2);
     }