Other Property and Equipment Other Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Other Property and Equipment Held for Use and Estimated Useful Lives

A summary by asset class of (gains) or losses on sales of fixed assets for the years ended December 31, 2017, 2016 and 2015 is as follows:

	Years Ended December 31,
	2017			2016			2015
	($ in millions)
Buildings and land	$	(4	)	$	(1	)	$	3
Natural gas compressors	1			(10		)	—
Gathering systems and treating plants	—			—			1
Other	—			(1		)	—
Total net (gains) losses on sales of fixed assets	$	(3	)	$	(12	)	$	4

A summary of other property and equipment held for use and the estimated useful lives thereof is as follows:

	December 31,						Estimated Useful Life
	2017			2016
	($ in millions)						(in years)
Buildings and improvements	$	1,093		$	1,119		10 – 39
Computer equipment	345			337			5
Natural gas compressors	235			251			3 – 20
Land	126			139
Gathering systems and treating plants	2			2			20
Other	185			205			5 – 10
Total other property and equipment, at cost	1,986			2,053
Less: accumulated depreciation	(672		)	(632		)
Total other property and equipment, net	$	1,314		$	1,421

Other Property and Equipment Gains (Losses) on Sales of Fixed Assets

A summary by asset class of (gains) or losses on sales of fixed assets for the years ended December 31, 2017, 2016 and 2015 is as follows:

	Years Ended December 31,
	2017			2016			2015
	($ in millions)
Buildings and land	$	(4	)	$	(1	)	$	3
Natural gas compressors	1			(10		)	—
Gathering systems and treating plants	—			—			1
Other	—			(1		)	—
Total net (gains) losses on sales of fixed assets	$	(3	)	$	(12	)	$	4

A summary of other property and equipment held for use and the estimated useful lives thereof is as follows:

	December 31,						Estimated Useful Life
	2017			2016
	($ in millions)						(in years)
Buildings and improvements	$	1,093		$	1,119		10 – 39
Computer equipment	345			337			5
Natural gas compressors	235			251			3 – 20
Land	126			139
Gathering systems and treating plants	2			2			20
Other	185			205			5 – 10
Total other property and equipment, at cost	1,986			2,053
Less: accumulated depreciation	(672		)	(632		)
Total other property and equipment, net	$	1,314		$	1,421