diff --git a/src/CNPJ.php b/src/CNPJ.php
index aa5f112..700badf 100644
--- a/src/CNPJ.php
+++ b/src/CNPJ.php
@@ -2,21 +2,14 @@
 
 namespace Bissolli\ValidadorCpfCnpj;
 
-class CNPJ
+class CNPJ extends DocumentoAbstract
 {
-    /**
-     * Value to be validated
-     *
-     * @var string
-     */
-    public $value;
-
     /**
      * Invalid numbers
      *
      * @var string
      */
-    public $blacklist = [
+    protected $blacklist = [
         '00000000000000',
         '11111111111111',
         '22222222222222',
@@ -29,16 +22,6 @@ class CNPJ
         '99999999999999'
     ];
 
-    /**
-     * Create a new ValidaDocumento instance
-     *
-     * @param string $value
-     */
-    public function __construct($value = null)
-    {
-        $this->value = (string) preg_replace('/[^0-9]/', '', $value);
-    }
-
     /**
      * Check if it is a valid CNPJ number
      *
@@ -93,24 +76,4 @@ public function format()
 
         return $result;
     }
-
-    /**
-     * Get class name without namespace
-     *
-     * @return string
-     */
-    public function getClassName()
-    {
-        return 'CNPJ';
-    }
-
-    /**
-     * Get the raw value
-     *
-     * @return string
-     */
-    public function getValue()
-    {
-        return $this->value;
-    }
 }
diff --git a/src/CPF.php b/src/CPF.php
index 83c5259..419e945 100644
--- a/src/CPF.php
+++ b/src/CPF.php
@@ -2,21 +2,14 @@
 
 namespace Bissolli\ValidadorCpfCnpj;
 
-class CPF
+class CPF extends DocumentoAbstract
 {
-    /**
-     * Value to be validated
-     *
-     * @var string
-     */
-    public $value;
-
     /**
      * Invalid numbers
      *
      * @var string
      */
-    private $blacklist = [
+    protected $blacklist = [
         '00000000000',
         '11111111111',
         '22222222222',
@@ -29,16 +22,6 @@ class CPF
         '99999999999'
     ];
 
-    /**
-     * Create a new ValidaDocumento instance
-     *
-     * @param string $value
-     */
-    public function __construct($value = null)
-    {
-        $this->value = (string) preg_replace('/[^0-9]/', '', $value);
-    }
-
     /**
      * Check if it is a valid CPF number
      *
@@ -90,24 +73,4 @@ public function format()
 
         return $result;
     }
-
-    /**
-     * Get class name without namespace
-     *
-     * @return string
-     */
-    public function getClassName()
-    {
-        return 'CPF';
-    }
-
-    /**
-     * Get the raw value
-     *
-     * @return string
-     */
-    public function getValue()
-    {
-        return $this->value;
-    }
 }
diff --git a/src/Documento.php b/src/Documento.php
index 3c0ad5a..5cd54e1 100644
--- a/src/Documento.php
+++ b/src/Documento.php
@@ -2,7 +2,7 @@
 
 namespace Bissolli\ValidadorCpfCnpj;
 
-class Documento
+class Documento extends DocumentoAbstract
 {
     /**
      * Value to be validated
@@ -11,21 +11,6 @@ class Documento
      */
     public $obj;
 
-    /**
-     * Create a new Documento instance
-     *
-     * @param string $value
-     */
-    public function __construct($value = null)
-    {
-        $value = (string) preg_replace('/[^0-9]/', '', $value);
-
-        if (strlen($value) === 11)
-            $this->obj = new CPF($value);
-        else
-            $this->obj = new CNPJ($value);
-    }
-
     /**
      * Get document type
      *
@@ -68,4 +53,21 @@ public function getValue()
     {
         return $this->obj->getValue();
     }
+
+    /**
+     * Set the clean value
+     *
+     * @return self
+     */
+    public function setValue($value)
+    {
+        $value = (string) preg_replace('/[^0-9]/', '', $value);
+
+        if (strlen($value) === 11)
+            $this->obj = new CPF($value);
+        else
+            $this->obj = new CNPJ($value);
+
+        return $this;
+    }
 }
diff --git a/src/DocumentoAbstract.php b/src/DocumentoAbstract.php
new file mode 100644
index 0000000..99922b9
--- /dev/null
+++ b/src/DocumentoAbstract.php
@@ -0,0 +1,58 @@
+<?php
+
+namespace Bissolli\ValidadorCpfCnpj;
+
+abstract class DocumentoAbstract
+{
+    /**
+     * Value to be validated
+     *
+     * @var string
+     */
+    protected $value;
+
+    /**
+     * Create a new ValidaDocumento instance
+     *
+     * @param string $value
+     */
+    public function __construct($value = null)
+    {
+        if ($value) $this->setValue($value);
+    }
+
+
+    abstract public function isValid();
+    abstract public function format();
+
+    /**
+     * Get class name without namespace
+     *
+     * @return string
+     */
+    public function getClassName()
+    {
+        return substr(strrchr(get_class($this), '\\'), 1);
+    }
+
+    /**
+     * Get the raw value
+     *
+     * @return string
+     */
+    public function getValue()
+    {
+        return $this->value;
+    }
+
+    /**
+     * Set the clean value
+     *
+     * @return self
+     */
+    public function setValue($value)
+    {
+        $this->value = (string) preg_replace('/[^0-9]/', '', $value);
+        return $this;
+    }
+}