CIBlockDocument::GetDocumentType

static function GetDocumentType($documentId)
{
	if (mb_substr($documentId, 0, mb_strlen("iblock_")) == "iblock_")
		return $documentId;

	$documentId = intval($documentId);
	if ($documentId <= 0)
		throw new CBPArgumentNullException("documentId");

	$dbResult = CIBlockElement::GetList(array(), array("ID" => $documentId, "SHOW_NEW" => "Y", "SHOW_HISTORY" => "Y"), false, false, array("ID", "IBLOCK_ID"));
	$arResult = $dbResult->Fetch();
	if (!$arResult)
		throw new Exception("Element is not found");

	return "iblock_".$arResult["IBLOCK_ID"];
}