14. COMMITMENTS AND CONTINGENCIES a) Concentrations of Credit Risk Credit risk arises out of the failure of a counterparty to perform according to the terms of the contract. The Company's investment portfolio is managed pursuant to guidelines that follow prudent standards of diversification. The guidelines limit the allowable holdings of a single issue and issuers. The Company believes that there are no significant concentrations of credit risk associated with its investment portfolio. As of December 31, 2012 and 2011 , substantially all of the Company's cash and investments were held with one custodian. Insurance balances receivable primarily consist of net premiums due from insureds and reinsureds and reinsurance funds held balances . The Company believes that the counterparties to these receivables are able to meet, and will meet, all of their obligations. The Company's credit risk is further reduced by the contractual right to offset loss obligations or unearned premiums against premiums receivable. Consequently, the Company has not included any material allowance for doubtful accounts against the receivable balance. At December 31, 2012, insurance balances receivable included $322,153 receivable from a single counterparty for net premiums and funds held balances. b) Operating Leases The Company leases office space under operating leases expiring in various years through 2022. The following are future minimum rental payments as of December 31, 2012 : Amount 2013 $ 11,163 2014 10,541 2015 8,711 2016 7,986 2017 7,402 2018 through 2022 20,078 $ 65,881 Total rent expense for the years ended December 31, 2012 , 2011 and 2010 was $ 11,929 , $12,807 and $13,750, respectively. During the year ended December 31, 2010, the Company terminated one of its office leases and recognized a termination fee of $1,128. c) Producers T he three largest individual producers as a percentage of gross premiums written are as follows: Year Ended December 31, 2012 2011 2010 Marsh &amp; McLennan Companies, Inc. 25% 23% 24% Aon Corporatio