diff --git a/odoo/api.py b/odoo/api.py
index 72792c8fbb3..4c9214a3f2f 100644
--- a/odoo/api.py
+++ b/odoo/api.py
@@ -29,7 +29,7 @@ except ImportError:
     from decorator import decorator
 
 from .exceptions import AccessError, CacheMiss
-from .tools import frozendict, lazy_property, OrderedSet, Query, SQL, StackMap
+from .tools import clean_context, frozendict, lazy_property, OrderedSet, Query, SQL, StackMap
 from .tools.translate import _
 
 _logger = logging.getLogger(__name__)
@@ -469,16 +469,16 @@ def call_kw(model, name, args, kwargs):
 
 
 class Environment(Mapping):
-    """ An environment wraps data for ORM records:
+    """ The environment stores various contextual data used by the ORM:
 
-        - :attr:`cr`, the current database cursor;
-        - :attr:`uid`, the current user id;
-        - :attr:`context`, the current context dictionary;
-        - :attr:`su`, whether in superuser mode.
+    - :attr:`cr`: the current database cursor (for database queries);
+    - :attr:`uid`: the current user id (for access rights checks);
+    - :attr:`context`: the current context dictionary (arbitrary metadata);
+    - :attr:`su`: whether in superuser mode.
 
-        It provides access to the registry by implementing a mapping from model
-        names to new api models. It also holds a cache for records, and a data
-        structure to manage recomputations.
+    It provides access to the registry by implementing a mapping from model
+    names to models. It also holds a cache for records, and a data
+    structure to manage recomputations.
     """
     def reset(self):
         """ Reset the transaction, see :meth:`Transaction.reset`. """
@@ -545,22 +545,30 @@ class Environment(Mapping):
     def __call__(self, cr=None, user=None, context=None, su=None):
         """ Return an environment based on ``self`` with modified parameters.
 
-            :param cr: optional database cursor to change the current cursor
-            :param user: optional user/user id to change the current user
-            :param context: optional context dictionary to change the current context
-            :param su: optional boolean to change the superuser mode
-            :type context: dict
-            :type user: int or :class:`~odoo.addons.base.models.res_users`
-            :type su: bool
+        :param cr: optional database cursor to change the current cursor
+        :type cursor: :class:`~odoo.sql_db.Cursor`
+        :param user: optional user/user id to change the current user
+        :type user: int or :class:`res.users record<~odoo.addons.base.models.res_users.Users>`
+        :param dict context: optional context dictionary to change the current context
+        :param bool su: optional boolean to change the superuser mode
+        :returns: environment with specified args (new or existing one)
+        :rtype: :class:`Environment`
         """
         cr = self.cr if cr is None else cr
         uid = self.uid if user is None else int(user)
-        context = self.context if context is None else context
+        if context is None:
+            context = clean_context(self.context) if su and not self.su else self.context
         su = (user is None and self.su) if su is None else su
         return Environment(cr, uid, context, su)
 
     def ref(self, xml_id, raise_if_not_found=True):
-        """Return the record corresponding to the given ``xml_id``."""
+        """ Return the record corresponding to the given ``xml_id``.
+
+        :param str xml_id: record xml_id, under the format ``<module.id>``
+        :param bool raise_if_not_found: whether the method should raise if record is not found
+        :returns: Found record or None
+        :raise ValueError: if record wasn't found and ``raise_if_not_found`` is True
+        """
         res_model, res_id = self['ir.model.data']._xmlid_to_res_model_res_id(
             xml_id, raise_if_not_found=raise_if_not_found
         )
@@ -592,7 +600,7 @@ class Environment(Mapping):
         """Return the current user (as an instance).
 
         :returns: current user - sudoed
-        :rtype: :class:`~odoo.addons.base.models.res_users`"""
+        :rtype: :class:`res.users record<~odoo.addons.base.models.res_users.Users>`"""
         return self(su=True)['res.users'].browse(self.uid)
 
     @lazy_property
@@ -604,7 +612,7 @@ class Environment(Mapping):
 
         :raise AccessError: invalid or unauthorized `allowed_company_ids` context key content.
         :return: current company (default=`self.user.company_id`), with the current environment
-        :rtype: res.company
+        :rtype: :class:`res.company record<~odoo.addons.base.models.res_company.Company>`
 
         .. warning::
 
@@ -634,7 +642,7 @@ class Environment(Mapping):
 
         :raise AccessError: invalid or unauthorized `allowed_company_ids` context key content.
         :return: current companies (default=`self.user.company_ids`), with the current environment
-        :rtype: res.company
+        :rtype: :class:`res.company recordset<~odoo.addons.base.models.res_company.Company>`
 
         .. warning::