Rate Matters	3 Months Ended
Mar. 31, 2016
Public Utilities, General Disclosures [Abstract]
Rate Matters	Rate Matters Except to the extent noted below, the circumstances set forth in Note 11 to the consolidated financial statements included in PSCo’s Annual Report on Form 10-K for the year ended Dec. 31, 2015, appropriately represent, in all material respects, the current status of other rate matters, and are incorporated herein by reference. Pending Regulatory Proceedings — CPUC Annual Electric Earnings Tests — As part of an annual earnings test, PSCo must share with customers’ earnings that exceed the authorized return on equity (ROE) threshold of 9.83 percent for 2015 through 2017. In April 2016, PSCo filed the 2015 earnings test, proposing an electric customer refund obligation of $14.9 million, subject to review by the CPUC. The proposed refund obligation related to the 2015 earnings test was accrued for as of March 31, 2016. The current estimate of the 2016 earnings test, based on annual forecasted information, did not result in the recognition of a liability as of March 31, 2016.

Rate Matters

Except to the extent noted below, the circumstances set forth in Note 11 to the consolidated financial statements included in PSCo’s Annual Report on Form 10-K for the year ended Dec. 31, 2015, appropriately represent, in all material respects, the current status of other rate matters, and are incorporated herein by reference.

Pending Regulatory Proceedings — CPUC

Annual Electric Earnings Tests — As part of an annual earnings test, PSCo must share with customers’ earnings that exceed the authorized return on equity (ROE) threshold of 9.83 percent for 2015 through 2017. In April 2016, PSCo filed the 2015 earnings test, proposing an electric customer refund obligation of $14.9 million, subject to review by the CPUC. The proposed refund obligation related to the 2015 earnings test was accrued for as of March 31, 2016. The current estimate of the 2016 earnings test, based on annual forecasted information, did not result in the recognition of a liability as of March 31, 2016.