Recurring Fair Value Measurements (Details) - USD ($)		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Return Cash Collateral		$ 32,000,000		$ 32,000,000		$ 32,000,000
Reclaim Cash Collateral		12,000,000		12,000,000		15,000,000
Commodity Trading
Changes in Level 3 Commodity Derivatives [Roll Forward]
Balance at beginning of period		28,000,000	$ 64,000,000	29,000,000	$ 35,000,000
Purchases		5,000,000	3,000,000	42,000,000	49,000,000
Settlements		(21,000,000)	(19,000,000)	(48,000,000)	(51,000,000)
Gains (losses) recognized in earnings	[1]	1,000,000	0	(9,000,000)	0
Net gains recognized as regulatory assets and liabilities		2,000,000	0	1,000,000	15,000,000
Balance at end of period		15,000,000	$ 48,000,000	15,000,000	$ 48,000,000
Transfers Level 3, Net		0
Other Current Assets
Derivatives, Fair Value [Line Items]
Derivative Asset, Net		61,000,000		61,000,000		87,000,000
Other Noncurrent Assets
Derivatives, Fair Value [Line Items]
Derivative Asset, Net		22,000,000		22,000,000		34,000,000
Other Current Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liability, Net		73,000,000		73,000,000		61,000,000
Other Noncurrent Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liability, Net		178,000,000		178,000,000		129,000,000
Fair Value Measured on a Recurring Basis | Other Current Assets
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		93,000,000		93,000,000		127,000,000
Netting	[2]	(35,000,000)		(35,000,000)		(44,000,000)
Derivative Asset, Net		58,000,000		58,000,000		83,000,000
Fair Value Measured on a Recurring Basis | Other Current Assets | Level 1
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		3,000,000		3,000,000		4,000,000
Fair Value Measured on a Recurring Basis | Other Current Assets | Level 2
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		49,000,000		49,000,000		96,000,000
Fair Value Measured on a Recurring Basis | Other Current Assets | Level 3
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		41,000,000		41,000,000		27,000,000
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		58,000,000		58,000,000		98,000,000
Netting	[2]	(34,000,000)		(34,000,000)		(44,000,000)
Derivative Asset, Net		24,000,000		24,000,000		54,000,000
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Electric Commodity
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		28,000,000		28,000,000		25,000,000
Netting	[2]	(1,000,000)		(1,000,000)		0
Derivative Asset, Net		27,000,000		27,000,000		25,000,000
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Natural Gas Commodity
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		7,000,000		7,000,000		4,000,000
Netting	[2]	0		0		0
Derivative Asset, Net		7,000,000		7,000,000		4,000,000
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Level 1 | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		3,000,000		3,000,000		4,000,000
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Level 1 | Electric Commodity
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		0		0		0
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Level 1 | Natural Gas Commodity
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		0		0		0
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Level 2 | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		42,000,000		42,000,000		92,000,000
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Level 2 | Electric Commodity
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		0		0		0
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Level 2 | Natural Gas Commodity
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		7,000,000		7,000,000		4,000,000
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Level 3 | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		13,000,000		13,000,000		2,000,000
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Level 3 | Electric Commodity
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		28,000,000		28,000,000		25,000,000
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Level 3 | Natural Gas Commodity
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		0		0		0
Fair Value Measured on a Recurring Basis | Other Noncurrent Assets
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		49,000,000		49,000,000		32,000,000
Netting	[2]	(41,000,000)		(41,000,000)		(14,000,000)
Derivative Asset, Net		8,000,000		8,000,000		18,000,000
Fair Value Measured on a Recurring Basis | Other Noncurrent Assets | Level 1
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		5,000,000		5,000,000		0
Fair Value Measured on a Recurring Basis | Other Noncurrent Assets | Level 2
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		39,000,000		39,000,000		27,000,000
Fair Value Measured on a Recurring Basis | Other Noncurrent Assets | Level 3
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		5,000,000		5,000,000		5,000,000
Fair Value Measured on a Recurring Basis | Other Noncurrent Assets | Other Derivative Instruments | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		49,000,000		49,000,000		32,000,000
Netting	[2]	(41,000,000)		(41,000,000)		(14,000,000)
Derivative Asset, Net		8,000,000		8,000,000		18,000,000
Fair Value Measured on a Recurring Basis | Other Noncurrent Assets | Other Derivative Instruments | Level 1 | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		5,000,000		5,000,000		0
Fair Value Measured on a Recurring Basis | Other Noncurrent Assets | Other Derivative Instruments | Level 2 | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		39,000,000		39,000,000		27,000,000
Fair Value Measured on a Recurring Basis | Other Noncurrent Assets | Other Derivative Instruments | Level 3 | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		5,000,000		5,000,000		5,000,000
Fair Value Measured on a Recurring Basis | Other Current Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liability, Gross		103,000,000		103,000,000		101,000,000
Netting	[2]	(47,000,000)		(47,000,000)		(60,000,000)
Derivative Liability, Net		56,000,000		56,000,000		41,000,000
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Level 1
Derivatives, Fair Value [Line Items]
Derivative Liability, Gross		3,000,000		3,000,000		4,000,000
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Level 2
Derivatives, Fair Value [Line Items]
Derivative Liability, Gross		88,000,000		88,000,000		95,000,000
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Level 3
Derivatives, Fair Value [Line Items]
Derivative Liability, Gross		12,000,000		12,000,000		2,000,000
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Other Derivative Instruments | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative Liability, Gross		56,000,000		56,000,000		94,000,000
Netting	[2]	(46,000,000)		(46,000,000)		(60,000,000)
Derivative Liability, Net		10,000,000		10,000,000		34,000,000
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Other Derivative Instruments | Electric Commodity
Derivatives, Fair Value [Line Items]
Derivative Liability, Gross		1,000,000		1,000,000		0
Netting	[2]	(1,000,000)		(1,000,000)		0
Derivative Liability, Net		0		0		0
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Other Derivative Instruments | Natural Gas Commodity
Derivatives, Fair Value [Line Items]
Derivative Liability, Gross		6,000,000		6,000,000		0
Netting	[2]	0		0		0
Derivative Liability, Net		6,000,000		6,000,000		0
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Other Derivative Instruments | Level 1 | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative Liability, Gross		3,000,000		3,000,000		4,000,000
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Other Derivative Instruments | Level 1 | Electric Commodity
Derivatives, Fair Value [Line Items]
Derivative Liability, Gross		0		0		0
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Other Derivative Instruments | Level 1 | Natural Gas Commodity
Derivatives, Fair Value [Line Items]
Derivative Liability, Gross		0		0		0
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Other Derivative Instruments | Level 2 | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative Liability, Gross		42,000,000		42,000,000		88,000,000
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Other Derivative Instruments | Level 2 | Electric Commodity
Derivatives, Fair Value [Line Items]
Derivative Liability, Gross		0		0		0
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Other Derivative Instruments | Level 2 | Natural Gas Commodity
Derivatives, Fair Value [Line Items]
Derivative Liability, Gross		6,000,000		6,000,000		0
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Other Derivative Instruments | Level 3 | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative Liability, Gross		11,000,000		11,000,000		2,000,000
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Other Derivative Instruments | Level 3 | Electric Commodity
Derivatives, Fair Value [Line Items]
Derivative Liability, Gross		1,000,000		1,000,000		0
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Other Derivative Instruments | Level 3 | Natural Gas Commodity
Derivatives, Fair Value [Line Items]
Derivative Liability, Gross		0		0		0
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Designated as Hedging Instrument | Interest Rate Swap
Derivatives, Fair Value [Line Items]
Netting	[2]	0		0		0
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Designated as Hedging Instrument | Cash Flow Hedges | Interest Rate Swap
Derivatives, Fair Value [Line Items]
Derivative Liability, Gross		40,000,000		40,000,000		7,000,000
Derivative Liability, Net		40,000,000		40,000,000		7,000,000
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Designated as Hedging Instrument | Level 1 | Cash Flow Hedges | Interest Rate Swap
Derivatives, Fair Value [Line Items]
Derivative Liability, Gross		0		0		0
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Designated as Hedging Instrument | Level 2 | Cash Flow Hedges | Interest Rate Swap
Derivatives, Fair Value [Line Items]
Derivative Liability, Gross		40,000,000		40,000,000		7,000,000
Fair Value Measured on a Recurring Basis | Other Current Liabilities | Designated as Hedging Instrument | Level 3 | Cash Flow Hedges | Interest Rate Swap
Derivatives, Fair Value [Line Items]
Derivative Liability, Gross		0		0		0
Fair Value Measured on a Recurring Basis | Other Noncurrent Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liability, Gross		109,000,000		109,000,000		19,000,000
Netting	[2]	(10,000,000)		(10,000,000)		(17,000,000)
Derivative Liability, Net		99,000,000		99,000,000		36,000,000
Fair Value Measured on a Recurring Basis | Other Noncurrent Liabilities | Level 1
Derivatives, Fair Value [Line Items]
Derivative Liability, Gross		2,000,000		2,000,000		0
Fair Value Measured on a Recurring Basis | Other Noncurrent Liabilities | Level 2
Derivatives, Fair Value [Line Items]
Derivative Liability, Gross		88,000,000		88,000,000		18,000,000
Fair Value Measured on a Recurring Basis | Other Noncurrent Liabilities | Level 3
Derivatives, Fair Value [Line Items]
Derivative Liability, Gross		19,000,000		19,000,000		1,000,000
Fair Value Measured on a Recurring Basis | Other Noncurrent Liabilities | Other Derivative Instruments | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative Liability, Gross		109,000,000		109,000,000		19,000,000
Netting	[2]	(10,000,000)		(10,000,000)		(17,000,000)
Derivative Liability, Net		99,000,000		99,000,000		36,000,000
Fair Value Measured on a Recurring Basis | Other Noncurrent Liabilities | Other Derivative Instruments | Level 1 | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative Liability, Gross		2,000,000		2,000,000		0
Fair Value Measured on a Recurring Basis | Other Noncurrent Liabilities | Other Derivative Instruments | Level 2 | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative Liability, Gross		88,000,000		88,000,000		18,000,000
Fair Value Measured on a Recurring Basis | Other Noncurrent Liabilities | Other Derivative Instruments | Level 3 | Commodity Trading
Derivatives, Fair Value [Line Items]
Derivative Liability, Gross		19,000,000		19,000,000		1,000,000
Fair Value, Measurements, Nonrecurring | Other Current Assets | PPAs
Derivatives, Fair Value [Line Items]
Derivative Asset, Net	[3]	3,000,000		3,000,000		4,000,000
Fair Value, Measurements, Nonrecurring | Other Noncurrent Assets | PPAs
Derivatives, Fair Value [Line Items]
Derivative Asset, Net	[3]	14,000,000		14,000,000		16,000,000
Fair Value, Measurements, Nonrecurring | Other Current Liabilities | PPAs
Derivatives, Fair Value [Line Items]
Derivative Liability, Net	[3]	17,000,000		17,000,000		20,000,000
Fair Value, Measurements, Nonrecurring | Other Noncurrent Liabilities | PPAs
Derivatives, Fair Value [Line Items]
Derivative Liability, Net	[3]	$ 79,000,000		$ 79,000,000		$ 93,000,000

[1] ^(a)  These amounts relate to commodity derivatives held at the end of the period.

[2] Xcel Energy nets derivative instruments and related collateral in its consolidated balance sheet when supported by a legally enforceable master netting agreement, and all derivative instruments and related collateral amounts were subject to master netting agreements at Sept. 30, 2019 and Dec. 31, 2018. At both Sept. 30, 2019 and Dec. 31, 2018, derivative assets and liabilities include $32 million of obligations to return cash collateral. At Sept. 30, 2019 and Dec. 31, 2018, derivative assets and liabilities include rights to reclaim cash collateral of $12 million and $15 million, respectively. Counterparty netting amounts presented exclude settlement receivables and payables and non-derivative amounts that may be subject to the same master netting agreements.

[3] During 2006, Xcel Energy qualified these contracts under the normal purchase exception. Based on this qualification, contracts are no longer adjusted to fair value and the previous carrying value of these contracts is being amortized over the remaining contract lives along with the offsetting regulatory assets and liabilities.