Goodwill and other intangible assets (Tables)

6 Months Ended

Jun. 30, 2021

Goodwill And Intangible Assets Disclosure [Abstract]

Reconciliation of the change in goodwill

Reconciliations of the changes in the carrying value of goodwill for the first six months of 2021 and for the year ended December 31, 2020 follow (in millions).

	June 30, 2021			December 31, 2020
Balance at beginning of year	$	73,734		$	81,882
Acquisitions of businesses		25			1,758
Impairment charges		—			(10,033	)
Other, including foreign currency translation		(1	)		127
Balance at end of period*	$	73,758		$	73,734

* Net of accumulated goodwill impairments of $11.0 billion as of June 30, 2021 and December 31, 2020.

Schedule of intangible assets

Other intangible assets and related accumulated amortization are summarized as follows (in millions).

	June 30, 2021				December 31, 2020
	Gross carrying amount		Accumulated amortization		Gross carrying amount		Accumulated amortization
Insurance and other:
Customer relationships	$	27,310	$	6,113	$	27,374	$	5,756
Trademarks and trade names		5,176		790		5,206		779
Patents and technology		4,667		3,314		4,766		3,313
Other		3,328		1,411		3,339		1,375
	$	40,481	$	11,628	$	40,685	$	11,223
Railroad, utilities and energy:
Customer relationships	$	678	$	380	$	678	$	361
Trademarks, trade names and other		1,003		121		1,003		98
	$	1,681	$	501	$	1,681	$	459