Goodwill (Tables)

12 Months Ended

Dec. 31, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Goodwill

The following is the summary of change in the carrying amount of goodwill for the years ended December 31:

	2017		2016
	(In millions)
Balance as of January 1	$	2,286	$	2,018
Goodwill attributable to Gas Storage and Pipelines acquisition	7		268
Balance at December 31	$	2,293	$	2,286