Commitments and Contingencies Leases (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Lessee, Lease, Description [Line Items]
Operating Lease, Weighted Average Discount Rate, Percent		4.10%
Operating Lease ROU Assets
Gross operating lease ROU assets		$ 1,843
Accumulated amortization		(171)
Net operating lease ROU assets		1,672	$ 0
Finance Lease ROU Assets
Gross finance lease ROU assets		222	222
Accumulated amortization		(83)	(77)
Net finance lease ROU assets		139	145
Components of Lease Expense
Operating Lease, Cost	[1]	255	248	$ 246
Finance Lease, Right-of-Use Asset, Amortization		6	6	5
Finance Lease, Interest Expense		19	19	20
Finance Lease, Cost		25	25	25
Short-term Lease, Cost		5	5	5
Operating Lease Commitments after Adoption of ASC Topic 842
2020		262
2021		267
2022		253
2023		239
2024		230
Thereafter		865
Total minimum obligation		2,116
Interest component of obligation		(373)
Present value of minimum obligation		1,743
Less current portion		(194)
Noncurrent operating and finance lease liabilities		$ 1,549	0
Operating Lease, Weighted Average Remaining Lease Term		9 years 3 months 18 days
Finance Lease, Liability, Payment, Due [Abstract]
2020	[2]	$ 14
2021	[2]	14
2022	[2]	12
2023	[2]	12
2024	[2]	12
Thereafter	[2]	207
Total minimum obligation	[2]	271
Interest component of obligation	[2]	(190)
Present value of minimum obligation	[2]	81
Finance Lease, Liability, Current	[2]	(4)
Finance Lease, Liability, Noncurrent	[2]	$ 77
Finance Lease, Weighted Average Remaining Lease Term	[2]	37 years
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2019			239
2020			234
2021			235
2022			221
2023			208
Thereafter			1,037
Capital Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2019			14
2020			14
2021			14
2022			12
2023			12
Thereafter			220
Total minimum obligation			286
Interest component of obligation			(201)
Capital Lease Obligations			85
Purchased Power Agreements
Operating Lease ROU Assets
Gross operating lease ROU assets		$ 1,642
Components of Lease Expense
Operating Lease, Cost		221	210	210
Operating Lease Commitments after Adoption of ASC Topic 842
2020	[3],[4]	236
2021	[3],[4]	238
2022	[3],[4]	225
2023	[3],[4]	214
2024	[3],[4]	208
Thereafter	[3],[4]	750
Total minimum obligation	[3],[4]	1,871
Interest component of obligation	[3],[4]	(321)
Present value of minimum obligation	[3],[4]	1,550
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2019			207
2020			208
2021			210
2022			197
2023			186
Thereafter			883
Gas Storage Facilities [Member]
Finance Lease ROU Assets
Gross finance lease ROU assets		201	201
Property, Plant and Equipment, Other Types [Member]
Operating Lease ROU Assets
Gross operating lease ROU assets		201
Components of Lease Expense
Operating Lease, Cost	[5]	34	38	$ 36
Operating Lease Commitments after Adoption of ASC Topic 842
2020		26
2021		29
2022		28
2023		25
2024		22
Thereafter		115
Total minimum obligation		245
Interest component of obligation		(52)
Present value of minimum obligation		193
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2019			32
2020			26
2021			25
2022			24
2023			22
Thereafter			154
Pipelines [Member]
Finance Lease ROU Assets
Gross finance lease ROU assets		$ 21	$ 21
WYCO, Inc. [Member]
Lessee, Lease, Description [Line Items]
Equity Method Investment, Ownership Percentage		50.00%	50.00%
Mankato Energy Center [Member] | NSP Minnesota | Purchased Power Agreements
Operating Lease Commitments after Adoption of ASC Topic 842
Noncurrent operating and finance lease liabilities		$ 400

[1] PPA capacity payments are included in electric fuel and purchased power on the consolidated statements of income. Expense for other operating leases is included in O&M expense and electric fuel and purchased power.

[2] Excludes certain amounts related to Xcel Energy’s 50% ownership interest in WYCO.

[3] Amounts do not include PPAs accounted for as executory contracts and/or contingent payments, such as energy payments on renewable PPAs.

[4] PPA operating leases contractually expire at various dates through 2033.

[5] Includes short-term lease expense of $5 million for 2019, 2018 and 2017.