Migrating id column to BIGINT?

[robocoder]

Our legacy system has id defined in all the entity classes as:

    /**
     * @ORM\Id
     * @ORM\Column(type="integer")
     * @ORM\GeneratedValue(strategy="AUTO")
     *
     * @var integer
     */
    protected $id;

Any tips/gotchas on migrating this to MySQL's bigint?