Borrowings and Other Financing Instruments Borrowings and Other Financing Instruments, Capital Stock (Details) - $ / shares	Dec. 31, 2018	Jun. 29, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Preferred Stock, Shares Authorized (in shares)	10,000,000
Preferred Stock, Par Value (in dollars per share)	$ 1
Preferred Stock, Shares Outstanding (in shares)	0
Common Stock, Shares Outstanding (in shares)		508,898,420
Xcel Energy Inc.
Debt Instrument [Line Items]
Preferred Stock, Shares Authorized (in shares)	7,000,000
Preferred Stock, Par Value (in dollars per share)	$ 100
Preferred Stock, Shares Outstanding (in shares)	0		0
Common Stock, Shares Authorized (in shares)	1,000,000,000
Common Stock, Par Value (in dollars per share)	$ 2.50
Common Stock, Shares Outstanding (in shares)	514,036,787		507,762,881
PSCo
Debt Instrument [Line Items]
Preferred Stock, Shares Authorized (in shares)	10,000,000
Preferred Stock, Par Value (in dollars per share)	$ 0.01
Preferred Stock, Shares Outstanding (in shares)	0		0
SPS
Debt Instrument [Line Items]
Preferred Stock, Shares Outstanding (in shares)			0