How to get the entityType from the lookup field coming from odata in mscrm 2011

Dear all;

i am geting the lookup field value from odata call which is coming fine but i wan tto know the Entitytype of the value 

i am tring this but not working

[{ id: ProTypeData[0].CustomerId.Id, name: ProTypeData[0].CustomerId.Name, entityType: ProTypeData[0].CustomerId.entityType}]