The carrying amount of goodwill for each of the Company’s operating segments for the years ended December 31, 2018 and 2017 is as follows (in thousands):

	December 31,						December 31,						December 31,
	2016		Acquisition		Impairment		2017		Acquisition		Impairment		2018
Television	$	35,912		4,637		—	$	40,549		—		—	$	40,549
Radio		—		—		—		—		—		—		—
Digital (1)		14,169		16,011		—		30,180		3,563		—		33,743
Consolidated	$	50,081	$	20,648	$	—	$	70,729	$	3,563	$	—	$	74,292

(1)	Amount reported as of and for the year ended December 31, 2017 has been revised. See Note 3.

The composition of the Company’s acquired intangible assets and the associated accumulated amortization as of December 31, 2018 and 2017 is as follows (in thousands):

			2018						2017
	Weighted average remaining life in years		Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
Intangible assets subject to amortization:
Television network affiliation agreements		8	$	67,489	$	56,950	$	10,539	$	67,489	$	55,560	$	11,929
Customer base		5		10,045		5,044		5,001		9,146		3,839		5,307
Pre-sold advertising contracts and other		6		38,857		31,799		7,058		37,755		28,233		9,522
Total assets subject to amortization:			$	116,391	$	93,793	$	22,598	$	114,390	$	87,632	$	26,758
Intangible assets not subject to amortization:
FCC licenses and spectrum usage rights								254,598						251,163
Total intangible assets							$	277,196					$	277,921

The aggregate amount of amortization expense for the years ended December 31, 2018, 2017 and 2016 was approximately $6.1 million, $5.9 million and $3.5 million, respectively. Estimated amortization expense for each of the years ended December 31, 2019 through 2023 is as follows (in thousands):

The Company has identified each of its three operating segments to be separate reporting units: television broadcasting, radio broadcasting, and digital media. The carrying values of the reporting units are determined by allocating all applicable assets (including goodwill) and liabilities based upon the unit in which the assets are employed and to which the liabilities relate, considering the methodologies utilized to determine the fair value of the reporting units.

Goodwill and indefinite life intangibles are not amortized but are tested annually for impairment, or more frequently, if events or changes in circumstances indicate that the assets might be impaired. The annual testing date is October 1.

The Company conducted a review of the fair value of the television reporting unit. As of the annual goodwill testing date, October 1, 2018, there was $40.5 million of goodwill in the television reporting unit. The estimated fair value of the television goodwill was determined by using a combination of a market approach and an income approach. The market approach estimates fair value by applying sales, earnings and cash flow multiples to the reporting unit’s operating performance. The multiples are derived from comparable publicly-traded companies with similar operating and investment characteristics to the television reporting unit. The market approach requires the Company to make a series of assumptions, such as selecting comparable companies and comparable transactions and transaction premiums.

The income approach estimates fair value based on the estimated future cash flows of the television reporting unit, discounted by an estimated weighted-average cost of capital that reflects current market conditions, which reflect the overall level of inherent risk of the reporting unit. The income approach also requires the Company to make a series of assumptions, such as discount rates, revenue projections, profit margin projections and terminal value multiples. The Company estimated the discount rate on a blended rate of return considering both debt and equity for comparable publicly-traded companies in the television industry. These comparable publicly-traded companies have similar size, operating characteristics and/or financial profiles to the television reporting unit. The Company also estimated the terminal value multiple based on comparable publicly-traded companies in the television industry. The Company estimated its revenue projections and profit margin projections based on internal forecasts about future performance.

Based on the assumptions and estimates described above, the television reporting unit fair value exceeded its carrying value by 48%, resulting in no impairment charge in 2018. The discount rate used in the fair value calculation of the television reporting unit was increased from prior year and expected cash flows of a component of the reporting unit were decreased from prior year to account for risk within the forecasts of the reporting unit. If that discount rate were to increase by 1%, the fair value of the television reporting unit would decrease by 6%. If the long term projected growth rate were to decrease by 0.5%, the fair value of the television reporting unit would decrease by 1%.

The Company also conducted a review of the fair value of the digital reporting unit. As of the annual goodwill testing date, October 1, 2018, there was $33.7 million of goodwill in the digital media reporting unit. The estimated fair value of the digital goodwill was determined by using a combination of a market approach and an income approach. The market approach estimates fair value by applying sales, earnings and cash flow multiples to the reporting unit’s operating performance. The multiples are derived from comparable publicly-traded companies with similar operating and investment characteristics to the digital reporting unit. The market approach requires the Company to make a series of assumptions, such as selecting comparable companies and comparable transactions and transaction premiums.

The income approach estimates fair value based on the estimated future cash flows of the digital reporting unit, discounted by an estimated weighted-average cost of capital that reflects current market conditions, which reflect the overall level of inherent risk of the reporting unit. The income approach also requires the Company to make a series of assumptions, such as discount rates, revenue projections, profit margin projections and terminal value multiples. The Company estimated the discount rate on a blended rate of return considering both debt and equity for comparable publicly-traded companies in the digital media industry. These comparable publicly-traded companies have similar size, operating characteristics and/or financial profiles to the digital reporting unit. The Company also estimated the terminal value multiple based on comparable publicly-traded companies in the digital media industry. The Company estimated its revenue projections and profit margin projections based on internal forecasts about future performance.

Based on the assumptions and estimates described above, the digital reporting unit fair value exceeded its carrying value by 1%, resulting in no impairment charge in 2018. The discount rate used in the fair value calculation of the digital reporting unit was increased from prior year and expected cash flows of a component of the reporting unit were decreased from prior year to account for risk within the forecasts of the reporting unit. If that discount rate were to increase by 1%, the fair value of the digital reporting unit would decrease by 5%. If the long term projected growth rate were to decrease by 0.5%, the fair value of the digital reporting unit would decrease by 1%.

Uncertain economic conditions, fiscal policy and other factors beyond the Company’s control potentially could have an adverse effect on the capital markets, which would affect the discount rate assumptions, terminal value estimates, transaction premiums and comparable transactions. Such uncertain economic conditions could also have an adverse effect on the fundamentals of the business and results of operations, which would affect the internal forecasts about future performance and terminal value estimates. Furthermore, such uncertain economic conditions could have a negative impact on the digital advertising industry in general or the industries of those customers who advertise with the digital reporting unit, including, among others, the automotive, financial and other services, telecommunications, travel and restaurant industries, which in the aggregate provide a significant amount of the historical and projected advertising revenue. The activities of competitors could have an adverse effect on the internal forecasts about future performance and terminal value estimates. Changes in technology or audience preferences, including increased competition from other forms of advertising-based mediums, could have an adverse effect on the internal forecasts about future performance, terminal value estimates and transaction premiums. Finally, the risk factors that the Company identifies from time to time in its SEC reports could have an adverse effect on the internal forecasts about future performance, terminal value estimates and transaction premiums.

There can be no assurance that the estimates and assumptions made for the purpose of the Company’s goodwill impairment testing will prove to be accurate predictions of the future. If the assumptions regarding internal forecasts of future performance of the reporting unit are not achieved, if market conditions change and affect the discount rate, or if there are lower comparable transactions and transaction premiums, the Company may be required to record goodwill impairment charges in future periods. It is not possible at this time to determine if any such future change in the Company’s assumptions would have an adverse impact on the valuation models and result in impairment, or if it does, whether such impairment charge would be material.

The Company did not have any goodwill in its radio reporting unit at December 31, 2018 and 2017.

There were no events that occurred subsequent to the annual impairment testing date that suggest that it is more likely than not that the fair value of any of the Company’s reporting units is less than the respective carrying amount.

The Company also conducted a review of the fair value of the television and radio FCC licenses in 2018 and 2017. The estimated fair value of indefinite life intangible assets is determined by an income approach. The income approach estimates fair value based on the estimated future cash flows of each market cluster that a hypothetical buyer would expect to generate, discounted by an estimated weighted-average cost of capital that reflects current market conditions, which reflect the level of inherent risk. The income approach requires the Company to make a series of assumptions, such as discount rates, revenue projections, profit margin projections and terminal value multiples. The Company estimates the discount rates on a blended rate of return considering both debt and equity for comparable publicly-traded companies. These comparable publicly-traded companies have similar size, operating characteristics and/or financial profiles to the Company. The Company also estimated the terminal value multiple based on comparable publicly-traded companies. The Company estimated the revenue projections and profit margin projections based on various market clusters signal coverage of the markets and industry information for an average station within a given market. The information for each market cluster includes such things as estimated market share, estimated capital start-up costs, population, household income, retail sales and other expenditures that would influence advertising expenditures. Alternatively, some stations under evaluation have had limited relevant cash flow history due to planned or actual conversion of format or upgrade of station signal. The assumptions the Company makes about cash flows after conversion are based on the performance of similar stations in similar markets and potential proceeds from the sale of the assets. Based on the assumptions and estimates, the Company did not record impairment of FCC licenses for the years ended December 31, 2018 and 2017.