We have two operating and reportable segments: (1) Software Products and (2) Professional Services. We assess goodwill for impairment at the reporting unit level. Our reporting units are determined based on the components of our operating segments that constitute a business for which discrete financial information is available and for which operating results are regularly reviewed by segment management. Our reporting units are the same as our operating segments.

As of June 27, 2020, goodwill and acquired intangible assets in the aggregate attributable to our Software Products segment was $1,807.3 million and attributable to our Professional Services segment was $45.1 million. As of September 30, 2019, goodwill and acquired intangible assets in the aggregate attributable to our Software Products segment was $1,362.4 million and attributable to our Professional Services segment was $45.7 million. Acquired intangible assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying value of the asset may not be recoverable. We evaluate goodwill for impairment in the third quarter of our fiscal year, or on an interim basis if an event occurs or circumstances change that would, more likely than not, reduce the fair value of a reporting segment below its carrying value. Factors we consider important, on an overall company basis and segment basis, when applicable, that could trigger an impairment review include significant under-performance relative to historical or projected future operating results, significant changes in our use of the acquired assets or the strategy for our overall business, significant negative industry or economic trends, a significant decline in our stock price for a sustained period and a reduction of our market capitalization relative to net book value.

We completed our annual goodwill impairment review as of June 27, 2020 based on a quantitative assessment. To conduct these tests of goodwill, the fair value of the reporting unit is compared to its carrying value. If the reporting unit’s carrying value exceeds its fair value, we record an impairment loss equal to the difference between the carrying value of goodwill and its estimated fair value. We estimate the fair values of our reporting units using discounted cash flow valuation models. Those models require estimates of future revenues, profits, capital expenditures, working capital, terminal values based on revenue multiples, and discount rates for each reporting unit. We estimate these amounts by evaluating historical trends, current budgets and operating plans, including consideration of the impact of the COVID-19 pandemic on our future results, and industry data. The estimated fair value of each reporting unit significantly exceeds its carrying value as of June 27, 2020.

(in thousands)	June 27, 2020						September 30, 2019
	Gross Carrying Amount		Accumulated Amortization		Net Book Value		Gross Carrying Amount		Accumulated Amortization		Net Book Value
Goodwill (not amortized)					$	1,605,204					$	1,238,179
Intangible assets with finite lives (amortized):
Purchased software	$	437,441	$	299,962	$	137,479	$	377,359	$	278,144	$	99,215
Capitalized software		22,877		22,877		—		22,877		22,877		—
Customer lists and relationships		414,084		311,117		102,967		355,931		288,828		67,103
Trademarks and trade names		22,541		15,814		6,727		18,891		15,260		3,631
Other		3,952		3,952		—		3,910		3,910		—
	$	900,895	$	653,722	$	247,173	$	778,968	$	609,019	$	169,949
Total goodwill and acquired intangible assets					$	1,852,377					$	1,408,128

(in thousands)	Software Products		Professional Services		Total
Balance, October 1, 2019	$	1,196,064	$	42,115	$	1,238,179
Onshape acquisition		364,910		—		364,910
Foreign currency translation adjustment		2,043		72		2,115
Balance, June 27, 2020	$	1,563,017	$	42,187	$	1,605,204

The aggregate amortization expense for intangible assets with finite lives was classified in our Consolidated Statements of Operations as follows:

(in thousands)	Three months ended				Nine months ended
	June 27, 2020		June 29, 2019		June 27, 2020		June 29, 2019
Amortization of acquired intangible assets	$	7,302	$	5,920	$	21,367	$	17,786
Cost of license revenue		6,857		6,873		20,535		20,432
Total amortization expense	$	14,159	$	12,793	$	41,902	$	38,218