4.Acquisitions, Goodwill and Intangible Assets:

Goodwill is tested for impairment at the reporting unit level (business unit or one level below a business unit) on an annual basis (October 1) 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. For purposes of evaluating goodwill for impairment, we have determined that our reporting units are the same as our business units except for the E&S Casualty and Aerospace & Programs business units for which reporting units are at the component level (“one level below”). Our consolidated balance sheet as of December 31, 2019 includes goodwill of acquired businesses of $44.7 million that is assigned to our business units as follows: Commercial Accounts business unit - $2.1 million; Commercial Auto business units - $21.3 million; E&S Casualty business unit - $6.3 million (comprised of $2.6 million for the primary/excess liability and public entity component and $3.7 million for the E&S package component); Aerospace & Programs business unit- $9.7 million (comprised entirely of the general aviation component); and Specialty Personal Lines business unit - $5.3 million. This amount has been recorded as a result of prior business acquisitions accounted for under the acquisition method of accounting. Under ASC 350, “Intangibles- Goodwill and Other,” goodwill is tested for impairment annually. We completed our last annual test for impairment on the first day of the fourth quarter of 2019 and determined that there was no impairment at that time.

The income approach to determining fair value computed the projections of the cash flows that the reporting unit was expected to generate converted into a present value equivalent through discounting. Significant assumptions in the income approach model included income projections, discount rates and terminal growth values. The income projections reflected an improved premium rate environment across most of our lines of business that continued throughout 2019. The income projections also included loss and LAE assumptions which reflected recent historical claim trends and the movement towards a more favorable pricing environment. The income projections also included assumptions for expense growth and investment yields which were based on business plans for each of our business units. The discount rate was based on a risk free rate plus a beta adjusted equity risk premium and specific company risk premium. The assumptions were based on historical experience (including factors such as prior year loss reserve development), expectations of future performance (including premium growth rates, premium rate increases and loss costs), expected market conditions and other factors requiring judgment and estimates. While we believe the assumptions used in these models were reasonable, the inherent uncertainty in predicting future performance and market conditions may change over time and influence the outcome of future testing.

During 2019 and 2018, we completed the first step prescribed by ASC 350 for testing for impairment and determined that there was no impairment.

We have obtained various intangible assets from several acquisitions. The table below details the gross and net carrying amounts of these assets by major category (in thousands):


	December 31
	2019		2018
Gross Carrying Amount:
Customer/agent relationships	$	32,177	$	32,177
Tradename		3,440		3,440
Management agreement		3,232		3,232
Non-compete & employment agreements		4,235		4,235
Insurance licenses		1,300		1,300
Total gross carrying amount		44,384		44,384

Accumulated Amortization:
Customer/agent relationships		(28,752)		(26,515)
Tradename		(3,078)		(2,847)
Management agreement		(3,232)		(3,232)
Non-compete & employment agreements		(4,235)		(4,235)
Total accumulated amortization		(39,297)		(36,829)
Total net carrying amount	$	5,087	$	7,555

Insurance licenses are not amortized because they have an indefinite life. We amortize definite-lived intangible assets straight line over their respective lives. The estimated aggregate amortization expense for definite-lived intangible assets for the next five years is as follows (in thousands):


2020	$	2,467
2021	$	503
2022	$	501
2023	$	316
2024	$	—

The weighted average amortization period for definite-lived intangible assets by major class is as follows:


		Years
Tradename		15
Customer/ agent relationships		15
Management agreement		4
Non-compete agreements		5

The aggregate weighted average period to amortize these assets is approximately 13 years.