Borrowings and Other Financing Instruments Borrowings and Other Financing Instruments, Long-Term Borrowings (Details) - SPS [Member] - Bonds [Member] - Series Due August 15, 2046 [Member] |
1 Months Ended |
|---|---|
|
Aug. 31, 2016
USD ($)
| |
| Debt Instrument [Line Items] | |
| Debt Instrument, Face Amount | $ 300,000,000 |
| Debt Instrument, Interest Rate, Stated Percentage | 3.40% |
| Debt Instrument, Maturity Date | Aug. 15, 2046 |