Goodwill is tested for impairment at the reporting unit level on an annual basis as of October 31, and between annual tests if an event occurs or circumstances change that would more-likely-than-not reduce the fair value of a reporting unit below its carrying value. We use a discounted expected future cash flow methodology (income approach) to estimate the fair value of our reporting units for purposes of goodwill impairment testing.

Although certain of Pursuit’s reporting units continue to operate at a loss due to travel restrictions as a result of the COVID-19 pandemic, we did not record any impairment charges during the first half of 2021 as there were no significant changes to our outlook for the future years and the risk profile of the reporting units had not changed.

Given the evolving nature of COVID-19, and the uncertain government and consumer reactions, the estimates and assumptions regarding expected future cash flows, discount rates, and terminal values used in our goodwill impairment analysis require considerable judgment and are based on our current estimates of market conditions, financial forecasts, and industry trends. These estimates, however, have inherent uncertainties and different assumptions could lead to materially different results including impairment charges in the future.

		June 30, 2021							December 31, 2020
(in thousands)	Useful Life (Years)	Gross Carrying Value		Accumulated Amortization			Net Carrying Value		Gross Carrying Value		Accumulated Amortization			Net Carrying Value
Intangible assets subject to amortization:
Customer contracts and relationships	6.2	$	37,926	$	(27,617	)	$	10,309	$	38,214	$	(26,288	)	$	11,926
Operating contracts and licenses	36.3		43,302		(2,854	)		40,448		42,012		(2,405	)		39,607
In-place lease	13.0		15,765		(900	)		14,865		15,347		(656	)		14,691
Tradenames	4.8		5,735		(2,508	)		3,227		5,940		(2,435	)		3,505
Non-compete agreements	0.5		790		(711	)		79		770		(616	)		154
Other	6.7		840		(123	)		717		818		(102	)		716
Total amortized intangible assets			104,358		(34,713	)		69,645		103,101		(32,502	)		70,599
Indefinite-lived intangible assets:
Business licenses			576		—			576		573		—			573
Other intangible assets		$	104,934	$	(34,713	)	$	70,221	$	103,674	$	(32,502	)	$	71,172

Intangible asset amortization expense was $1.6 million for the three months ended June 30, 2021 and $2.8 million for the six months ended June 30, 2021. Intangible asset amortization was $1.4 million for the three months ended June 30, 2020 and $3.6 million for the six months ended June 30, 2020. We recorded a non-cash impairment charge to intangible assets of $15.7 million during the six months ended June 30, 2020 related to our United States audio-visual production business. The duration and impact of COVID-19 may result in additional future impairment charges as facts and circumstances evolve.

At June 30, 2021, the estimated future amortization expense related to intangible assets subject to amortization is as follows: