Our intangible assets include the following:

Indefinite Life Intangible Assets

We have identified our FCC licenses and the XM trademark as indefinite life intangible assets after considering the expected use of the assets, the regulatory and economic environment within which they are used and the effects of obsolescence on their use.

We hold FCC licenses to operate our satellite digital audio radio service and provide ancillary services. The following table outlines the years in which each of our satellite licenses expires:

Prior to expiration, we are required to apply for a renewal of our FCC licenses.  The renewal and extension of our licenses, including temporary licenses, is reasonably certain at minimal cost, which is expensed as incurred.  Each of the FCC licenses authorizes us to use the broadcast spectrum, which is a renewable, reusable resource that does not deplete or exhaust over time.

Our annual impairment assessment of our indefinite intangible assets is performed as of the fourth quarter of each year. An assessment is performed at other times if an event occurs or circumstances change that would more likely than not reduce the fair value of the asset below its carrying value.  If the carrying value of the intangible assets exceeds its fair value, an impairment loss is recognized.  As of September 30, 2015, there were no indicators of impairment, and no impairment loss was recorded for intangible assets with indefinite lives during the three and nine months ended September 30, 2015 and 2014.

Definite Life Intangible Assets

Amortization expense for all definite life intangible assets was $12,824 and $13,642 for the three months ended September 30, 2015 and 2014, respectively, and $39,068 and $41,586 for the nine months ended September 30, 2015 and 2014, respectively.  Expected amortization expense for the remaining period in 2015, each of the fiscal years 2016 through 2019 and for periods thereafter is as follows: