NOTE 4. Goodwill and Intangible Assets

There were no acquisitions that closed during 2018. Purchased goodwill from acquisitions totaled $1.3 billion in 2017, none of which is deductible for tax purposes. The acquisition activity in the following table also includes the net impact of adjustments to the preliminary allocation of purchase price within the one year measurement-period following prior acquisitions, which increased goodwill by $7 million during 2018. The amounts in the “Translation and other” column in the following table primarily relate to changes in foreign currency exchange rates. The goodwill balance by business segment follows:

Goodwill


(Millions)	Industrial		Safety and Graphics		Health Care		Electronics and Energy		Consumer		Total Company
Balance as of December 31, 2016	$	2,536	$	3,324	$	1,609	$	1,489	$	208	$	9,166
Acquisition activity		—		1,296		6		—		—		1,302
Divestiture activity		—		(323)		—		—		—		(323)
Translation and other		142		122		67		35		2		368
Balance as of December 31, 2017		2,678		4,419		1,682		1,524		210		10,513
Acquisition activity		—		7		—		—		—		7
Divestiture activity		(4)		(8)		—		(260)		—		(272)
Translation and other		(60)		(93)		(28)		(14)		(2)		(197)
Balance as of December 31, 2018	$	2,614	$	4,325	$	1,654	$	1,250	$	208	$	10,051

Accounting standards require that goodwill be tested for impairment annually and between annual tests in certain circumstances such as a change in reporting units or the testing of recoverability of a significant asset group within a reporting unit. At 3M, reporting units correspond to a division.

As described in Note 18, effective in the first quarter of 2018, the Company changed its business segment reporting in its continuing effort to improve the alignment of its businesses around markets and customers. For any product changes that resulted in reporting unit changes, the Company applied the relative fair value method to determine the impact on goodwill of the associated reporting units. During the first quarter of 2018, the Company completed its assessment of any potential goodwill impairment for reporting units impacted by this new structure and determined that no impairment existed. The Company also completed its annual goodwill impairment test in the fourth quarter of 2018 for all reporting units and determined that no impairment existed. In addition, the Company had no impairments of goodwill in 2016 or 2017.

Acquired Intangible Assets

The carrying amount and accumulated amortization of acquired finite-lived intangible assets, in addition to the balance of non-amortizable intangible assets, as of December 31, follow:


	December 31,		December 31,
(Millions)	2018		2017
Customer related intangible assets	$	2,291	$	2,332
Patents		542		561
Other technology-based intangible assets		576		583
Definite-lived tradenames		664		678
Other amortizable intangible assets		125		207
Total gross carrying amount	$	4,198	$	4,361

Accumulated amortization — customer related		(998)		(874)
Accumulated amortization — patents		(487)		(489)
Accumulated amortization — other technology based		(333)		(292)
Accumulated amortization — definite-lived tradenames		(276)		(256)
Accumulated amortization — other		(88)		(162)
Total accumulated amortization	$	(2,182)	$	(2,073)

Total finite-lived intangible assets — net	$	2,016	$	2,288

Non-amortizable intangible assets (primarily tradenames)		641		648
Total intangible assets — net	$	2,657	$	2,936

Certain tradenames acquired by 3M are not amortized because they have been in existence for over 55 years, have a history of leading-market share positions, have been and are intended to be continuously renewed, and the associated products of which are expected to generate cash flows for 3M for an indefinite period of time.

Amortization expense for the years ended December 31 follows:


(Millions)	2018		2017		2016
Amortization expense	$	249	$	238	$	262

Expected amortization expense for acquired amortizable intangible assets recorded as of December 31, 2018 follows:


											After
(Millions)	2019		2020		2021		2022		2023		2023
Amortization expense	$	240	$	228	$	219	$	205	$	174	$	950

The preceding expected amortization expense is an estimate. Actual amounts of amortization expense may differ from estimated amounts due to additional intangible asset acquisitions, changes in foreign currency exchange rates, impairment of intangible assets, accelerated amortization of intangible assets and other events. 3M expenses the costs incurred to renew or extend the term of intangible assets.