RATE AND OTHER REGULATORY MATTERS (Tables)

3 Months Ended

Mar. 31, 2019

Public Utilities, General Disclosures [Line Items]

Schedule of Regulatory Assets [Table Text Block]

Millions of dollars	March 31, 2019		December 31, 2018
Regulatory Assets:
Unrecovered NND Project costs	$	138	$	127
Deferred employee benefit plan costs	16		16
Other unrecovered plant	14		14
DSM programs	16		14
Other	69		52
Regulatory assets - current	253		223
Unrecovered NND Project costs	2,607		2,641
AROs	335		380
Deferred employee benefit plan costs	252		256
Deferred losses on interest rate derivatives	297		442
Other unrecovered plant	76		79
DSM programs	51		51
Environmental remediation costs	23		24
Deferred storm damage costs	34		35
Deferred transmission operating costs	21		15
Other	114		123
Regulatory assets - noncurrent	3,810		4,046
Total Regulatory Assets	$	4,063	$	4,269

Schedule of Regulatory Liabilities [Table Text Block]

Regulatory Liabilities:
Monetization of guaranty settlement	$	67	$	61
Income taxes refundable through future rates	49		52
Reserve for refunds to electric utility customers	137		—
Other	9		13
Regulatory liabilities - current	262		126
Monetization of guaranty settlement	1,020		1,037
Income taxes refundable through future rates	837		607
Asset removal costs	549		541
Deferred gains on interest rate derivatives	70		75
Reserve for refunds to electric utility customers	846		—
Other	1		4
Regulatory liabilities - noncurrent	3,323		2,264
Total Regulatory Liabilities	$	3,585	$	2,390