Impairments (Tables)

6 Months Ended

Jun. 30, 2016

Asset Impairment Charges [Abstract]

Details of Impairment of Long-Lived Assets Held and Used by Asset

A summary of our impairments of fixed assets by asset class and other charges for the Current Quarter, the Prior Quarter, the Current Period and the Prior Period is as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
	2016		2015		2016		2015
	($ in millions)
Natural gas compressors	$	—	$	21	$	20	$	21
Buildings and land	—		—		7		—
Other	6		63		17		67
Total impairments of fixed assets and other	$	6	$	84	$	44	$	88