diff --git a/docs/reference/google.auth.app_engine.rst b/docs/reference/google.auth.app_engine.rst
index 4525c08..2142b6f 100644
--- a/docs/reference/google.auth.app_engine.rst
+++ b/docs/reference/google.auth.app_engine.rst
@@ -1,7 +1,7 @@
-google.auth.app_engine module
-=============================
+google.auth.app\_engine module
+==============================
 
 .. automodule:: google.auth.app_engine
-    :members:
-    :inherited-members:
-    :show-inheritance:
+   :members:
+   :inherited-members:
+   :show-inheritance:
diff --git a/docs/reference/google.auth.compute_engine.credentials.rst b/docs/reference/google.auth.compute_engine.credentials.rst
index ebe62c0..782d95f 100644
--- a/docs/reference/google.auth.compute_engine.credentials.rst
+++ b/docs/reference/google.auth.compute_engine.credentials.rst
@@ -1,7 +1,7 @@
-google.auth.compute_engine.credentials module
-=============================================
+google.auth.compute\_engine.credentials module
+==============================================
 
 .. automodule:: google.auth.compute_engine.credentials
-    :members:
-    :inherited-members:
-    :show-inheritance:
+   :members:
+   :inherited-members:
+   :show-inheritance:
diff --git a/docs/reference/google.auth.compute_engine.rst b/docs/reference/google.auth.compute_engine.rst
index 2e7b830..38785c8 100644
--- a/docs/reference/google.auth.compute_engine.rst
+++ b/docs/reference/google.auth.compute_engine.rst
@@ -1,10 +1,10 @@
-google.auth.compute_engine package
-==================================
+google.auth.compute\_engine package
+===================================
 
 .. automodule:: google.auth.compute_engine
-    :members:
-    :inherited-members:
-    :show-inheritance:
+   :members:
+   :inherited-members:
+   :show-inheritance:
 
 Submodules
 ----------
@@ -12,4 +12,3 @@
 .. toctree::
 
    google.auth.compute_engine.credentials
-
diff --git a/docs/reference/google.auth.credentials.rst b/docs/reference/google.auth.credentials.rst
index b710a8c..18d1d8c 100644
--- a/docs/reference/google.auth.credentials.rst
+++ b/docs/reference/google.auth.credentials.rst
@@ -2,6 +2,6 @@
 ==============================
 
 .. automodule:: google.auth.credentials
-    :members:
-    :inherited-members:
-    :show-inheritance:
+   :members:
+   :inherited-members:
+   :show-inheritance:
diff --git a/docs/reference/google.auth.crypt.rst b/docs/reference/google.auth.crypt.rst
index a3e2b12..0833e7f 100644
--- a/docs/reference/google.auth.crypt.rst
+++ b/docs/reference/google.auth.crypt.rst
@@ -2,9 +2,9 @@
 =========================
 
 .. automodule:: google.auth.crypt
-    :members:
-    :inherited-members:
-    :show-inheritance:
+   :members:
+   :inherited-members:
+   :show-inheritance:
 
 Submodules
 ----------
@@ -13,4 +13,3 @@
 
    google.auth.crypt.base
    google.auth.crypt.rsa
-
diff --git a/docs/reference/google.auth.environment_vars.rst b/docs/reference/google.auth.environment_vars.rst
index fe34849..5996e99 100644
--- a/docs/reference/google.auth.environment_vars.rst
+++ b/docs/reference/google.auth.environment_vars.rst
@@ -1,7 +1,7 @@
-google.auth.environment_vars module
-===================================
+google.auth.environment\_vars module
+====================================
 
 .. automodule:: google.auth.environment_vars
-    :members:
-    :inherited-members:
-    :show-inheritance:
+   :members:
+   :inherited-members:
+   :show-inheritance:
diff --git a/docs/reference/google.auth.exceptions.rst b/docs/reference/google.auth.exceptions.rst
index d603eaf..c87a7f2 100644
--- a/docs/reference/google.auth.exceptions.rst
+++ b/docs/reference/google.auth.exceptions.rst
@@ -2,6 +2,6 @@
 =============================
 
 .. automodule:: google.auth.exceptions
-    :members:
-    :inherited-members:
-    :show-inheritance:
+   :members:
+   :inherited-members:
+   :show-inheritance:
diff --git a/docs/reference/google.auth.iam.rst b/docs/reference/google.auth.iam.rst
index 8a5edb4..8472ed7 100644
--- a/docs/reference/google.auth.iam.rst
+++ b/docs/reference/google.auth.iam.rst
@@ -2,6 +2,6 @@
 ======================
 
 .. automodule:: google.auth.iam
-    :members:
-    :inherited-members:
-    :show-inheritance:
+   :members:
+   :inherited-members:
+   :show-inheritance:
diff --git a/docs/reference/google.auth.impersonated_credentials.rst b/docs/reference/google.auth.impersonated_credentials.rst
index 653708e..f139ccf 100644
--- a/docs/reference/google.auth.impersonated_credentials.rst
+++ b/docs/reference/google.auth.impersonated_credentials.rst
@@ -2,6 +2,6 @@
 ============================================
 
 .. automodule:: google.auth.impersonated_credentials
-    :members:
-    :inherited-members:
-    :show-inheritance:
+   :members:
+   :inherited-members:
+   :show-inheritance:
diff --git a/docs/reference/google.auth.jwt.rst b/docs/reference/google.auth.jwt.rst
index c58be5f..c7c2fdf 100644
--- a/docs/reference/google.auth.jwt.rst
+++ b/docs/reference/google.auth.jwt.rst
@@ -2,6 +2,6 @@
 ======================
 
 .. automodule:: google.auth.jwt
-    :members:
-    :inherited-members:
-    :show-inheritance:
+   :members:
+   :inherited-members:
+   :show-inheritance:
diff --git a/docs/reference/google.auth.rst b/docs/reference/google.auth.rst
index 53ab699..f6ea073 100644
--- a/docs/reference/google.auth.rst
+++ b/docs/reference/google.auth.rst
@@ -2,18 +2,18 @@
 ===================
 
 .. automodule:: google.auth
-    :members:
-    :inherited-members:
-    :show-inheritance:
+   :members:
+   :inherited-members:
+   :show-inheritance:
 
 Subpackages
 -----------
 
 .. toctree::
 
-    google.auth.compute_engine
-    google.auth.crypt
-    google.auth.transport
+   google.auth.compute_engine
+   google.auth.crypt
+   google.auth.transport
 
 Submodules
 ----------
@@ -27,4 +27,3 @@
    google.auth.iam
    google.auth.impersonated_credentials
    google.auth.jwt
-
diff --git a/docs/reference/google.auth.transport.grpc.rst b/docs/reference/google.auth.transport.grpc.rst
index e16d1d8..f9f3442 100644
--- a/docs/reference/google.auth.transport.grpc.rst
+++ b/docs/reference/google.auth.transport.grpc.rst
@@ -2,6 +2,6 @@
 =================================
 
 .. automodule:: google.auth.transport.grpc
-    :members:
-    :inherited-members:
-    :show-inheritance:
+   :members:
+   :inherited-members:
+   :show-inheritance:
diff --git a/docs/reference/google.auth.transport.requests.rst b/docs/reference/google.auth.transport.requests.rst
index f31830c..5f0c23c 100644
--- a/docs/reference/google.auth.transport.requests.rst
+++ b/docs/reference/google.auth.transport.requests.rst
@@ -2,6 +2,6 @@
 =====================================
 
 .. automodule:: google.auth.transport.requests
-    :members:
-    :inherited-members:
-    :show-inheritance:
+   :members:
+   :inherited-members:
+   :show-inheritance:
diff --git a/docs/reference/google.auth.transport.rst b/docs/reference/google.auth.transport.rst
index 1f802c3..48e2e05 100644
--- a/docs/reference/google.auth.transport.rst
+++ b/docs/reference/google.auth.transport.rst
@@ -2,9 +2,9 @@
 =============================
 
 .. automodule:: google.auth.transport
-    :members:
-    :inherited-members:
-    :show-inheritance:
+   :members:
+   :inherited-members:
+   :show-inheritance:
 
 Submodules
 ----------
@@ -14,4 +14,3 @@
    google.auth.transport.grpc
    google.auth.transport.requests
    google.auth.transport.urllib3
-
diff --git a/docs/reference/google.auth.transport.urllib3.rst b/docs/reference/google.auth.transport.urllib3.rst
index 339c77e..667bb09 100644
--- a/docs/reference/google.auth.transport.urllib3.rst
+++ b/docs/reference/google.auth.transport.urllib3.rst
@@ -2,6 +2,6 @@
 ====================================
 
 .. automodule:: google.auth.transport.urllib3
-    :members:
-    :inherited-members:
-    :show-inheritance:
+   :members:
+   :inherited-members:
+   :show-inheritance:
diff --git a/docs/reference/google.oauth2.credentials.rst b/docs/reference/google.oauth2.credentials.rst
index ca978d1..d3bdc16 100644
--- a/docs/reference/google.oauth2.credentials.rst
+++ b/docs/reference/google.oauth2.credentials.rst
@@ -2,6 +2,6 @@
 ================================
 
 .. automodule:: google.oauth2.credentials
-    :members:
-    :inherited-members:
-    :show-inheritance:
+   :members:
+   :inherited-members:
+   :show-inheritance:
diff --git a/docs/reference/google.oauth2.id_token.rst b/docs/reference/google.oauth2.id_token.rst
index db38b60..fbe6eab 100644
--- a/docs/reference/google.oauth2.id_token.rst
+++ b/docs/reference/google.oauth2.id_token.rst
@@ -1,7 +1,7 @@
-google.oauth2.id_token module
-=============================
+google.oauth2.id\_token module
+==============================
 
 .. automodule:: google.oauth2.id_token
-    :members:
-    :inherited-members:
-    :show-inheritance:
+   :members:
+   :inherited-members:
+   :show-inheritance:
diff --git a/docs/reference/google.oauth2.rst b/docs/reference/google.oauth2.rst
index adb9403..4f1df07 100644
--- a/docs/reference/google.oauth2.rst
+++ b/docs/reference/google.oauth2.rst
@@ -2,9 +2,9 @@
 =====================
 
 .. automodule:: google.oauth2
-    :members:
-    :inherited-members:
-    :show-inheritance:
+   :members:
+   :inherited-members:
+   :show-inheritance:
 
 Submodules
 ----------
@@ -14,4 +14,3 @@
    google.oauth2.credentials
    google.oauth2.id_token
    google.oauth2.service_account
-
diff --git a/docs/reference/google.oauth2.service_account.rst b/docs/reference/google.oauth2.service_account.rst
index cc4e438..8d8fcd3 100644
--- a/docs/reference/google.oauth2.service_account.rst
+++ b/docs/reference/google.oauth2.service_account.rst
@@ -1,7 +1,7 @@
-google.oauth2.service_account module
-====================================
+google.oauth2.service\_account module
+=====================================
 
 .. automodule:: google.oauth2.service_account
-    :members:
-    :inherited-members:
-    :show-inheritance:
+   :members:
+   :inherited-members:
+   :show-inheritance:
diff --git a/docs/reference/google.rst b/docs/reference/google.rst
index fc63d1f..4b1e085 100644
--- a/docs/reference/google.rst
+++ b/docs/reference/google.rst
@@ -2,15 +2,14 @@
 ==============
 
 .. automodule:: google
-    :members:
-    :inherited-members:
-    :show-inheritance:
+   :members:
+   :inherited-members:
+   :show-inheritance:
 
 Subpackages
 -----------
 
 .. toctree::
 
-    google.auth
-    google.oauth2
-
+   google.auth
+   google.oauth2
diff --git a/google/oauth2/_client.py b/google/oauth2/_client.py
index 5121a32..eac01b7 100644
--- a/google/oauth2/_client.py
+++ b/google/oauth2/_client.py
@@ -102,13 +102,23 @@
         'content-type': _URLENCODED_CONTENT_TYPE,
     }
 
-    response = request(
-        method='POST', url=token_uri, headers=headers, body=body)
+    retry = 0
+    # retry to fetch token for maximum of two times if any internal failure
+    # occurs.
+    while True:
+        response = request(
+            method='POST', url=token_uri, headers=headers, body=body)
+        response_body = response.data.decode('utf-8')
 
-    response_body = response.data.decode('utf-8')
-
-    if response.status != http_client.OK:
-        _handle_error_response(response_body)
+        if response.status == http_client.OK:
+            break
+        else:
+            error_desc = json.loads(
+                response_body).get('error_description') or ''
+            if error_desc == 'internal_failure' and retry < 1:
+                retry += 1
+                continue
+            _handle_error_response(response_body)
 
     response_data = json.loads(response_body)
 
diff --git a/tests/oauth2/test__client.py b/tests/oauth2/test__client.py
index 5a4a567..6fc4c3b 100644
--- a/tests/oauth2/test__client.py
+++ b/tests/oauth2/test__client.py
@@ -106,6 +106,18 @@
         _client._token_endpoint_request(request, 'http://example.com', {})
 
 
+def test__token_endpoint_request_internal_failure_error():
+    request = make_request({'error': 'internal_failure',
+                            'error_description': 'internal_failure'},
+                           status=http_client.BAD_REQUEST)
+
+    with pytest.raises(exceptions.RefreshError):
+        _client._token_endpoint_request(
+            request, 'http://example.com',
+            {'error': 'internal_failure',
+             'error_description': 'internal_failure'})
+
+
 def verify_request_params(request, params):
     request_body = request.call_args[1]['body']
     request_params = urllib.parse.parse_qs(request_body)