Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2019

Fair Value Disclosures [Abstract]

Assets and Liabilities Measured at Fair Value on Recurring Basis

The following table presents, by level within the fair value hierarchy, our assets and liabilities that are measured at fair value on a recurring basis. The carrying amounts reported in the Consolidated Balance Sheets for cash and cash equivalents and restricted cash approximate fair value due to the nature of the instrument and/or the short-term maturity of these instruments.

	December 31, 2019								December 31, 2018
	Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3		Total
	(Millions)								(Millions)
Energy derivative assets	$	—	$	67	$	—	$	67	$	—	$	175	$	3	$	178
Energy derivative liabilities	$	—	$	91	$	—	$	91	$	—	$	37	$	—	$	37
Total debt(a)	$	—	$	2,400	$	—	$	2,400	$	—	$	2,414	$	—	$	2,414

__________

(a) The carrying value of total debt, excluding debt issuance costs, was $2,229 million and $2,509 million as of December 31, 2019 and 2018, respectively.