Goodwill and other intangible assets (Tables)

12 Months Ended

Dec. 31, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Reconciliation of the change in goodwill

Reconciliations of the changes in the carrying value of goodwill during 2018 and 2017 follows (in millions).

	December 31,
	2018			2017
Balance at beginning of year	$	81,258		$	79,486
Acquisitions of businesses		376			1,545
Other, including foreign currency translation		(609	)		227
Balance at end of year	$	81,025		$	81,258

Schedule of intangible assets

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

	December 31, 2018				December 31, 2017
	Gross carrying amount		Accumulated amortization		Gross carrying amount		Accumulated amortization
Insurance and other	$	40,493	$	8,994	$	40,225	$	7,707
Railroad, utilities and energy		1,011		362		988		324
	$	41,504	$	9,356	$	41,213	$	8,031
Trademarks and trade names	$	5,368	$	750	$	5,381	$	692
Patents and technology		4,446		2,790		4,341		2,493
Customer relationships		28,375		4,573		28,322		3,722
Other		3,315		1,243		3,169		1,124
	$	41,504	$	9,356	$	41,213	$	8,031