Asset Retirement Obligations (Tables)

12 Months Ended

Dec. 31, 2016

Asset Retirement Obligation Disclosure [Abstract]

Schedule of company's ARO obligations and related additions, reductions and accretion

The following table represents the balance of ARO obligations as of December 31, 2016 and 2015, along with the additions, reductions and accretion related to the Company's ARO obligations for the year ended December 31, 2016:

	(In millions)
Balance as of December 31, 2015	$	945
Revisions in estimates for current obligations	(103		)
Additions	49
Spending for current obligations	(8		)
Accretion — Expense	42
Accretion — Nuclear decommissioning	15
Balance as of December 31, 2016	$	940