What is Query for getting customers having multiple accounts?

 What is Query for getting customers having multiple accounts?
 and How to get customers having multiple accounts?

SELECT hca.account_number,rc.customer_name, hp.party_type,hp.party_name
 FROM hz_parties hp, hz_Cust_Accounts hca,ar.ra_customers rc
WHERE hp.party_id = hca.party_id
and rc.customer_id=hca.cust_Account_id
  AND hca.cust_account_id IN (
         SELECT   customer_id
             FROM ap_bank_account_uses_all bauses,
                  ap_bank_accounts_all bacct
            WHERE bauses.external_bank_account_id = bacct.bank_account_id
              AND primary_flag = 'Y'
         GROUP BY customer_id)
          HAVING COUNT (DISTINCT (external_bank_account_id)) > 1)