SELECT customer_details FROM Customers EXCEPT SELECT T1.customer_details FROM Customers AS T1 JOIN Customer_Policies AS T2 ON T1.customer_id  =  T2.customer_id
List the details of the customers who do not have any policies.
SELECT customer_details FROM Customers EXCEPT SELECT T1.customer_details FROM Customers AS T1 JOIN Customer_Policies AS T2 ON T1.customer_id = T2.customer_id
select customer_details from customers except select t1 . customer_details from customers as t1 join customer_policies as t2 on t1 . customer_id = t2 . customer_id
List the details of the customers who do not have any policies .