Rate Matters Rate Matters - PSCo (Details)	3 Months Ended
Mar. 31, 2017
PSCo \| CPUC Proceeding - Annual Electric Earnings Test 2015 through 2017
Public Utilities, General Disclosures [Line Items]
Public Utilities, Return on equity threshold for earnings sharing	9.83%

The return on equity used as a threshold in the public utility's annual earnings test for 2012-2014, as approved by a regulatory agency. Earnings exceeding this threshold are shared between customers and shareholders.

No definition available.

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration