(10)	Property, plant and equipment

A summary of property, plant and equipment of our insurance and other businesses follows (in millions).

 

		December 31,
		2018				2017
Land		$	2,536			$	2,523
Buildings and improvements			9,959				9,409
Machinery and equipment			22,574				21,190
Furniture, fixtures and other			4,758				4,519
			39,827				37,641
Accumulated depreciation			(19,199	)			(17,773	)
		$	20,628			$	19,868

 

A summary of property, plant and equipment of our railroad and our utilities and energy businesses follows (in millions). The utility generation, transmission and distribution systems and interstate natural gas pipeline assets are owned by regulated public utility and natural gas pipeline subsidiaries.

 

		December 31,
		2018				2017
Railroad:
Land, track structure and other roadway		$	59,509			$	57,408
Locomotives, freight cars and other equipment			13,016				12,543
Construction in progress			664				989
			73,189				70,940
Accumulated depreciation			(10,004	)			(8,627	)
			63,185				62,313
Utilities and energy:
Utility generation, transmission and distribution systems			77,288				74,660
Interstate natural gas pipeline assets			7,524				7,176
Independent power plants and other assets			8,324				7,499
Construction in progress			3,110				2,556
			96,246				91,891
Accumulated depreciation			(27,651	)			(26,020	)
			68,595				65,871
		$	131,780			$	128,184

Depreciation expense for each of the three years ending December 31, 2018 is summarized below (in millions).

 

		2018				2017				2016
Insurance and other		$	2,186			$	2,116			$	2,017
Railroad, utilities and energy			5,098				4,852				4,639
		$	7,284			$	6,968			$	6,656

 

 

(11)	Equipment held for lease

Equipment held for lease is summarized below (in millions). Equipment held for lease includes railcars, aircraft, over-the-road trailers, intermodal tank containers, cranes, storage units and furniture. In conjunction with the adoption of ASC 606, we recorded a net asset of approximately $3.5 billion related to aircraft sold under fractional aircraft ownership programs in aircraft. Such amount included cost of approximately $5.3 billion, net of accumulated depreciation of $1.8 billion. We also recorded other liabilities of approximately $3.5 billion for estimated aircraft repurchase liabilities and unearned lease revenues, substantially offsetting the amount recorded in aircraft. See Note 1(w).

 

		December 31,
		2018				2017
Railcars		$	8,862			$	8,352
Aircraft			7,376				1,456
Other equipment held for lease			4,379				3,967
			20,617				13,775
Accumulated depreciation			(6,319	)			(3,608)
		$	14,298			$	10,167

Depreciation expense for equipment held for lease was $1,102 million in 2018, $751 million in 2017 and $755 million in 2016. As of December 31, 2018, the minimum future lease rentals to be received on equipment held for lease were as follows (in millions): 2019 – $2,493; 2020 – $1,771; 2021 – $1,222; 2022 – $779; 2023 – $421; and thereafter – $377.