Asset Retirement Obligations (Tables)

12 Months Ended

Dec. 31, 2020

Asset Retirement Obligation Disclosure [Abstract]

Schedule of Asset Retirement Obligations [Table Text Block]

AROs consist of the following (in millions):

	As of December 31,
	2020		2019
Trojan decommissioning activities	$	139	$	137
Utility plant	118		126
Non-utility property	34		16
Total asset retirement obligations	291		279
Less: current portion *	21		16
Noncurrent asset retirement obligations	$	270	$	263

*    Current portion of AROs are classified within Accrued expenses and other current liabilities in the consolidated balance sheets.

Schedule of Change in Asset Retirement Obligation [Table Text Block]

The following is a summary of the changes in the Company’s AROs (in millions):

	Years Ended December 31,
	2020		2019		2018
Balance as of beginning of year	$	279	$	197	$	167
Liabilities incurred	3		—		—
Liabilities settled	(18)		(9)		(5)
Accretion expense	10		9		8
Revisions in estimated cash flows	17		82		27
Balance as of end of year	$	291	$	279	$	197