Goodwill and Other Intangible Assets

Goodwill

There were no changes in the carrying amount of goodwill during 2018 and 2017. Goodwill is reviewed annually for impairment and more frequently if potential impairment indicators exist. No impairment indicators were identified during 2018 and 2017. All of the Company's goodwill is associated with the Property and Casualty business segment (See Note 19. Segment Information for additional information on the reportable business segment).

Other Intangible Assets

The following table presents the components of other intangible assets:



	Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount		Useful Lives
	(Amounts in thousands)							(in years)
As of December 31, 2018
Customer relationships	$	53,048	$	(47,897	)	$	5,151	11
Trade names	15,400		(6,417		)	8,983		24
Technology	4,300		(4,300		)	—		10
Insurance license	1,400		—			1,400		Indefinite
Total intangible assets, net	$	74,148	$	(58,614	)	$	15,534

As of December 31, 2017
Customer relationships	$	52,890	$	(43,617	)	$	9,273	11
Trade names	15,400		(5,775		)	9,625		24
Technology	4,300		(3,870		)	430		10
Insurance license	1,400		—			1,400		Indefinite
Total intangible assets, net	$	73,990	$	(53,262	)	$	20,728

Other intangible assets are reviewed annually for impairment and more frequently if potential impairment indicators exist. No impairment indicators were identified during 2018 and 2017.

Other intangible assets with definite useful lives are amortized on a straight-line basis over their useful lives. Other intangible assets amortization expense was $5.5 million, $5.4 million, and $6.1 million for the years ended December 31, 2018, 2017, and 2016, respectively. None of the intangible assets with definite useful lives are anticipated to have a residual value.

The following table presents the estimated future amortization expense related to other intangible assets as of December 31, 2018:



Year Ending December 31,	Amortization Expense
	(Amounts in thousands)
2019	$	5,036
2020	889
2021	869
2022	845
2023	681
Thereafter	5,814
Total	$	14,134