j. Revenue Recognition 1) Interest income  We recognize interest income from investments in commercial mortgage loans, mezzanine loans, and preferred equity interests on a yield to maturity basis. Certain of our commercial mortgage loans, mezzanine loans and preferred equity interests provide for the accrual of interest at specified rates that differ from current payment terms. Interest income is recognized on such loans, the majority of which were originated prior to 2011, at the accrual rate subject to managements determination that accrued interest and outstanding principal are ultimately collectible. Management will cease accruing interest on these loans when it determines that collection of the interest income is not probable based on the value of the underlying collateral using discounted cash flow models and market based assumptions. The accrued interest receivable associated with these loans as of September 30, 2017 and December 31, 2016 was $26,432 and $29,845, respectively. During the nine months ended September 30, 2017, the accrued interest receivable of $3,636 related to one of these loans was determined to be uncollectible and was written off as a reduction to investment interest income. These loans are considered to be impaired when the total contractual amount owed exceeds the estimated value of the underlying collateral. Three of these loans, with an unpaid principal balance of $24,214 were considered to be impaired as of September 30, 2017. One of these loans, with an unpaid principal balance of $12,869 was considered to be impaired as of December 31, 2016. For investments that we do not elect to record at fair value under FASB ASC Topic 825, Financial Instruments, origination fees and direct loan origination costs are deferred and amortized to net investment income, using the effective interest method, over the contractual life of the underlying loan security or loan, in accordance with FASB ASC Topic 310, Receivables. For investments that we elect to record at fair value under FASB ASC T