Goodwill and other intangible assets (Tables)

6 Months Ended

Jun. 30, 2020

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 2020 and for the year ended December 31, 2019 follow (in millions).

	June 30, 2020			December 31, 2019
Balance at beginning of year	$	81,882		$	81,025
Acquisitions of businesses		18			890
Impairment charges		(9,996	)		—
Other, including foreign currency translation		(151	)		(33	)
Balance at end of period	$	71,753		$	81,882

Schedule of intangible assets

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

	June 30, 2020				December 31, 2019
	Gross carrying amount		Accumulated amortization		Gross carrying amount		Accumulated amortization
Insurance and other:
Trademarks and trade names	$	5,180	$	769	$	5,286	$	759
Patents and technology		4,658		3,167		4,560		3,032
Customer relationships		27,311		5,346		27,943		5,025
Other		3,300		1,320		3,364		1,286
	$	40,449	$	10,602	$	41,153	$	10,102
Railroad, utilities and energy:
Trademarks and trade names	$	212	$	28	$	212	$	26
Customer relationships		678		343		678		324
Other		113		60		113		58
	$	1,003	$	431	$	1,003	$	408