Intangible Assets

Our intangible assets include the following:



		June 30, 2016							December 31, 2015
	Weighted Average Useful Lives	Gross Carrying Value		Accumulated Amortization			Net Carrying Value		Gross Carrying Value		Accumulated Amortization			Net Carrying Value
Indefinite life intangible assets:
FCC licenses	Indefinite	$	2,083,654	$	—		$	2,083,654	$	2,083,654	$	—		$	2,083,654
Trademark	Indefinite	250,000		—			250,000		250,000		—			250,000
Definite life intangible assets:
Subscriber relationships	9 years	380,000		(351,214		)	28,786		380,000		(336,822		)	43,178
OEM relationships	15 years	220,000		(39,111		)	180,889		220,000		(31,778		)	188,222
Licensing agreements	12 years	45,289		(28,819		)	16,470		45,289		(26,977		)	18,312
Proprietary software	8 years	27,215		(18,783		)	8,432		27,215		(17,752		)	9,463
Developed technology	10 years	2,000		(1,583		)	417		2,000		(1,483		)	517
Leasehold interests	7.4 years	—		—			—		132		(132		)	—
Total intangible assets		$	3,008,158	$	(439,510	)	$	2,568,648	$	3,008,290	$	(414,944	)	$	2,593,346

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:



FCC satellite licenses		Expiration year
SIRIUS FM-1*		2017
SIRIUS FM-2*		2017
SIRIUS FM-3*		2017
SIRIUS FM-5		2025
SIRIUS FM-6		2022
XM-3		2021
XM-4		2022
XM-5		2018

* As of April 7, 2016, these satellites were no longer being used to transmit satellite radio. We plan to deorbit these satellites during 2016.

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

Our annual impairment assessment of our identifiable 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 June 30, 2016, there were no indicators of impairment, and no impairment loss was recorded for intangible assets with indefinite lives during the three and six months ended June 30, 2016 and 2015.

Definite Life Intangible Assets

Amortization expense for all definite life intangible assets was $12,258 and $13,021 for the three months ended June 30, 2016 and 2015, respectively, and $24,698 and $26,244 for the six months ended June 30, 2016 and 2015, respectively. Expected amortization expense for the remaining period in 2016, each of the fiscal years 2017 through 2020 and for periods thereafter is as follows:



Years ending December 31,	Amount
2016 (remaining)	$	23,847
2017	34,882
2018	19,463
2019	19,026
2020	18,446
Thereafter	119,330
Total definite life intangible assets, net	$	234,994