Goodwill and other intangible assets (Tables)

9 Months Ended

Sep. 30, 2015

Goodwill and Intangible Assets Disclosure [Abstract]

Reconciliation of the change in goodwill

The change in the carrying value of goodwill for the first nine months of 2015 and the year ended December 31, 2014 is summarized as follows (in millions).

	September 30,     2015		December 31,     2014
Balance at beginning of year		$  60,714		$57,011
Acquisitions of businesses		2,388		4,006
Other, including foreign currency translation		(410)		(303)
Balance at end of period		$  62,692		$60,714

Schedule of intangible assets

Intangible assets other than goodwill are included in other assets and are summarized as follows (in millions).

	September 30, 2015				December 31, 2014
	Gross carrying    amount		Accumulated  amortization		Gross carrying  amount		Accumulated  amortization
Insurance and other		$14,783		$5,243		$13,714		$4,476
Railroad, utilities and energy		885		225		2,254		1,551
		$15,668		$5,468		$15,968		$6,027
Trademarks and trade names		$  3,054		$   742		$  3,117		$   599
Patents and technology		4,225		1,992		5,425		3,133
Customer relationships		5,510		2,041		5,603		1,768
Other		2,879		693		1,823		527
		$15,668		$5,468		$15,968		$  6,027