Ok, I found a good solution to solve my problem.

Modules required

• Helper
• Devel (this is not necessary)

Steps

• Enable Helper module;
• Enable Devel module;
• Enable the block Execute PHP;
• Paste and execute this code in the block: FieldChangeHelper::changeType('field_myintegerfield', 'number_decimal');
• Edit display format for node where the field is being used;
• Edit Views where the field is being used to fix the format settings (If necessary);

If you don't want use Devel and can use Drush:

• Enable Helper module;

• create a new file in root Drupal folder, i.e. name it: intToField.php

  <?php FieldChangeHelper::changeType('field_myintegerfield', 'number_decimal'); ?>

• launch the drush command: drush src intToField.php

• Delete the file;

• Edit display format for node where the field is being used;

• Edit Views where the field is being used to fix the format settings (If necessary);

Ok, I found a good solution to solve my problem.

Modules required

• Helper
• Devel (this is not strictly necessary)

Steps

• Enable Helper module;
• Enable Devel module;
• Enable the block Execute PHP;
• Paste and execute this code in the block: FieldChangeHelper::changeType('field_myintegerfield', 'number_decimal');
• Edit display format for node where the field is being used;
• Edit Views where the field is being used to fix the format settings (If necessary);

If you don't want use Devel and can use Drush:

• Enable Helper module;

• create a new file in root Drupal folder, i.e. name it: intToField.php

  <?php FieldChangeHelper::changeType('field_myintegerfield', 'number_decimal'); ?>

• launch the drush command: drush src intToField.php

• Delete the file;

• Edit display format for node where the field is being used;

• Edit Views where the field is being used to fix the format settings (If necessary);