Property, plant and equipment (Tables)

12 Months Ended

Dec. 31, 2011

Insurance and Other [Member]

Property, plant and equipment

Property, plant and equipment of our insurance and other businesses is comprised of the following (in millions).

	Ranges  of estimated useful life		December 31,
			2011			2010
Land		—	$	940		$	744
Buildings and improvements		3 – 40 years		5,429			4,661
Machinery and equipment		3 – 25 years		13,589			11,573
Furniture, fixtures and other		2 – 20 years		2,397			1,932
Assets held for lease		12 – 30 years		5,997			5,832
				28,352			24,742
Accumulated depreciation				(10,175	)		(9,001	)
			$	18,177		$	15,741

Railroad, Utilities and Energy [Member]

Property, plant and equipment

Property, plant and equipment of our railroad, utilities and energy businesses is comprised of the following (in millions).

	Ranges of estimated  useful life	December 31,
		2011			2010
Railroad:
Land	—	$	5,925		$	5,901
Track structure and other roadway	5 – 100 years		36,760			35,463
Locomotives, freight cars and other equipment	5 – 37 years		5,533			4,329
Construction in progress	—		885			453
Utilities and energy:
Utility generation, distribution and transmission system	5 – 80 years		40,180			37,643
Interstate pipeline assets	3 – 80 years		6,245			5,906
Independent power plants and other assets	3 – 30 years		1,106			1,097
Construction in progress	—		1,559			1,456
			98,193			92,248
Accumulated depreciation			(15,979	)		(14,863	)
		$	82,214		$	77,385