As of December 31, 2017 and 2016, intangible assets associated with the favorable lease terms included an amount of $1,150 and $1,180, respectively related to purchase options for the vessels (see also Note 2(n)). During the year ended December 31, 2017, acquisition costs of $10,398 and accumulated amortization of $7,001 of favorable lease terms considered impaired and were written off resulting in a loss of $3,397. During the year ended December 31, 2016, acquisition costs of $70,937 and accumulated amortization of $57,930 of favorable lease terms were written off resulting in a loss of $13,007. This write-off resulted from the early redelivery of one vessel.

As of December 31, 2016, the intangible liability associated with the unfavorable lease terms included an amount of  $0, related to purchase options held by third parties (see also Note 2(n)). During the year ended December 31, 2016, acquisition costs of $24,721 and accumulated amortization of $17,406 of unfavorable lease terms were written off resulting in an income of $7,315. This write-off resulted from the early redelivery of one vessel. As of December 31, 2016, no purchase options held by third parties have been exercised.