Note H — Goodwill and Other Intangible Assets

We assess goodwill and indefinite-lived intangible assets for impairment annually on October 1st, 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.

The following table summarizes the activity in goodwill for the periods indicated:


	For the Six Months Ended June 30, 2019
	Patient Care						Products & Services						Consolidated
	Goodwill,		Accumulated		Goodwill,		Goodwill,		Accumulated		Goodwill,		Goodwill,		Accumulated		Goodwill,
(in thousands)	Gross		Impairment		Net		Gross		Impairment		Net		Gross		Impairment		Net
As of December 31, 2018	$	627,410	$	(428,668)		198,742	$	139,299	$	(139,299)		—	$	766,709	$	(567,967)		198,742
Additions from acquisitions		27,961		—		27,961		—		—		—		27,961		—		27,961
Measurement period adjustments		29		—		29		—		—		—		29		—		29
As of June 30, 2019	$	655,400	$	(428,668)	$	226,732	$	139,299	$	(139,299)	$	—	$	794,699	$	(567,967)	$	226,732


	For the Year Ended December 31, 2018
	Patient Care						Products & Services						Consolidated
	Goodwill,		Accumulated		Goodwill,		Goodwill,		Accumulated		Goodwill,		Goodwill,		Accumulated		Goodwill,
(in thousands)	Gross		Impairment		Net		Gross		Impairment		Net		Gross		Impairment		Net
As of December 31, 2017	$	625,011	$	(428,668)	$	196,343	$	139,299	$	(139,299)	$	—	$	764,310	$	(567,967)	$	196,343
Additions from acquisitions		2,399		—		2,399		—		—		—		2,399		—		2,399
As of December 31, 2018	$	627,410	$	(428,668)	$	198,742	$	139,299	$	(139,299)	$	—	$	766,709	$	(567,967)	$	198,742

The balances related to intangible assets as of June 30, 2019 and December 31, 2018 are as follows:


	As of June 30, 2019

	Gross Carrying		Accumulated		Accumulated		Net Carrying
(in thousands)	Amount		Amortization		Impairment		Amount
Customer lists	$	27,825	$	(20,311)	$	—	$	7,514
Trade name		255		(138)		—		117
Patents and other intangibles		9,238		(5,216)		—		4,022
Definite-lived intangible assets		37,318		(25,665)		—		11,653
Indefinite-lived trade names		9,070		—		(4,953)		4,117
Total other intangible assets	$	46,388	$	(25,665)	$	(4,953)	$	15,770


	As of December 31, 2018
	Gross Carrying		Accumulated		Accumulated		Net Carrying
(in thousands)	Amount		Amortization		Impairment		Amount
Customer lists	$	26,036	$	(19,051)	$	—	$	6,985
Trade name		255		(125)		—		130
Patents and other intangibles		9,391		(5,145)		—		4,246
Definite-lived intangible assets		35,682		(24,321)		—		11,361
Indefinite-lived trade names		9,070		—		(4,953)		4,117
Total other intangible assets	$	44,752	$	(24,321)	$	(4,953)	$	15,478

Total intangible amortization expense was approximately $1.1 million and $2.4 million for the three and six months ended June 30, 2019 and $1.8 million and $3.8 million for the three and six months ended June 30, 2018.

Estimated aggregate amortization expense for definite-lived intangible assets for each of the next five years ended December 31st and thereafter is as follows:


(in thousands)
2019 (remainder of the year)	$	2,235
2020		4,211
2021		1,628
2022		1,556
2023		914
Thereafter		1,109
Total	$	11,653