Goodwill and other intangible assets (Tables)

12 Months Ended

Dec. 31, 2019

Goodwill And Intangible Assets Disclosure [Abstract]

Reconciliation of the change in goodwill

Reconciliations of the changes in the carrying value of goodwill during 2019 and 2018 follows (in millions).

	December 31,
	2019			2018
Balance at beginning of year	$	81,025		$	81,258
Acquisitions of businesses		890			376
Other, including foreign currency translation		(33	)		(609	)
Balance at end of year	$	81,882		$	81,025

Schedule of intangible assets

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

	December 31, 2019				December 31, 2018
	Gross carrying amount		Accumulated amortization		Gross carrying amount		Accumulated amortization
Insurance and other:
Trademarks and trade names	$	5,286	$	759	$	5,152	$	727
Patents and technology		4,560		3,032		4,446		2,790
Customer relationships		27,943		5,025		27,697		4,287
Other		3,364		1,286		3,198		1,190
	$	41,153	$	10,102	$	40,493	$	8,994
Railroad, utilities and energy:
Trademarks and trade names	$	212	$	26	$	216	$	23
Customer relationships		678		324		678		286
Other		113		58		117		53
	$	1,003	$	408	$	1,011	$	362