Goodwill and other intangible assets (Tables)

9 Months Ended

Sep. 30, 2013

Reconciliation of the change in goodwill

A reconciliation of the change in the carrying value of goodwill is as follows (in millions).

	September 30, 2013			December 31, 2012
Balance at beginning of year	$	54,523		$	53,213
Acquisitions of businesses		322			1,442
Other, including foreign currency translation		(110	)		(132	)
Balance at end of period	$	54,735		$	54,523

Schedule of intangible assets

Intangible assets other than goodwill are included in other assets in our Consolidated Balance Sheets and are summarized by type as follows (in millions).

	September 30, 2013				December 31, 2012
	Gross carrying amount		Accumulated amortization		Gross carrying amount		Accumulated amortization
Insurance and other	$	12,013	$	3,525	$	11,737	$	2,994
Railroad, utilities and energy		2,198		1,147		2,163		913
	$	14,211	$	4,672	$	13,900	$	3,907
Trademarks and trade names	$	2,865	$	326	$	2,819	$	278
Patents and technology		5,162		2,470		5,014		2,059
Customer relationships		4,660		1,421		4,565		1,155
Other		1,524		455		1,502		415
	$	14,211	$	4,672	$	13,900	$	3,907