Goodwill and other intangible assets (Tables)

9 Months Ended

Sep. 30, 2019

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 nine months of 2019 and for the year ended December 31, 2018 follows (in millions).

	September 30, 2019			December 31, 2018
Balance at beginning of year	$	81,025		$	81,258
Acquisitions of businesses		279			376
Other, including foreign currency translation		(76	)		(609	)
Balance at end of period	$	81,228		$	81,025

Schedule of intangible assets

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

	September 30, 2019				December 31, 2018
	Gross carrying amount		Accumulated amortization		Gross carrying amount		Accumulated amortization
Insurance and other:
Trademarks and trade names	$	5,145	$	743	$	5,152	$	727
Patents and technology		4,524		2,973		4,446		2,790
Customer relationships		27,786		4,874		27,697		4,287
Other		3,169		1,246		3,198		1,190
	$	40,624	$	9,836	$	40,493	$	8,994
Railroad, utilities and energy:
Trademarks and trade names	$	216	$	27	$	216	$	23
Customer relationships		678		315		678		286
Other		117		56		117		53
	$	1,011	$	398	$	1,011	$	362