Auto width en tooltip de Bootstrap 3.x (Tooltip auto ajustado)

.tooltip-inner
{
	max-width: none;
	white-space: nowrap;
	background:white;
	border:1px solid lightgray;
	-webkit-box-shadow: 0px 3px 3px 0px rgba(0,0,0,0.3);
	-moz-box-shadow: 0px 3px 3px 0px rgba(0,0,0,0.3);
	box-shadow: 0px 3px 3px 0px rgba(0,0,0,0.3);
	color:gray;
	margin:0;
	padding:0;
}

.tooltip.bottom .tooltip-arrow
{
	top: 0;
	left: 50%;
	margin-left: -5px;
	border-bottom-color: lightgray; /* black */
	border-width: 0 5px 5px;
}

$('#txtNombre').tooltip({ "placement" : "right", "html" : true, "trigger" : "focus", "title" : "<div style=\"padding: 4px;\">Ingrese su nombre de usuarios.</div>" });