diff --git a/docs/simplesamlphp-sp-api.txt b/docs/simplesamlphp-sp-api.txt
index 07c5a35c364913e0efa79e19f3262fc0239c00c5..7ccb2ae53e261078ed91e181305841441b5a729b 100644
--- a/docs/simplesamlphp-sp-api.txt
+++ b/docs/simplesamlphp-sp-api.txt
@@ -195,6 +195,23 @@ The attributes will be returned as an associative array with the name of the att
     print('Hello, ' . htmlspecialchars($name));
 
 
+`getAuthData`
+---------------
+
+    mixed getAuthData(string $name)
+
+Retrieve the specified authentication data for the current session.
+NULL is returned if the user isn't authenticated.
+
+The available authentication data depends on the module used for authentication.
+See the [`saml:SP`](./saml:sp) reference for information about available SAML authentication data.
+
+### Example
+
+    $idp = $auth->getAuthData('saml:sp:IdP');
+    print(You are logged in from: ' . htmlspecialchars($idp));
+
+
 `getLoginURL`
 -------------
 
diff --git a/modules/saml/docs/sp.txt b/modules/saml/docs/sp.txt
index 9c7bc94f2fb113f78dcc8ff0dc4bc4c0c3fd16c1..f3c94092c371b6805a2ffe2061e5553cb8985ea7 100644
--- a/modules/saml/docs/sp.txt
+++ b/modules/saml/docs/sp.txt
@@ -42,6 +42,23 @@ All these parameters override the equivalent option from the configuration.
 :   *Note*: SAML 2 specific.
 
 
+Authentication data
+-------------------
+
+Some SAML-specific attributes are available to the application after authentication.
+To retrieve these attributes, the application can use the `getAuthData()`-function from the [SP API](./simplesamlphp-sp-api).
+The following attributes are available:
+
+`saml:sp:IdP`
+:   The entityID of the IdP the user is authenticated against.
+
+`saml:sp:NameID`
+:   The NameID the user was issued by the IdP.
+    This is an associative array with the various fields from the NameID.
+
+`saml:sp:SessionIndex`
+:   The SessionIndex we received from the IdP.
+
 
 Examples
 --------