Commitments and Contingencies, Legal Contingencies (Details)	1 Months Ended
Dec. 31, 2015	Jun. 30, 2019 USD ($)
Gas Trading Litigation
Legal Contingencies [Abstract]
Loss Contingency, Pending Claims, Number		2
PSCo \| Minimum \| Line Extension Disputes
Legal Contingencies [Abstract]
Loss Contingency, Number of Plaintiffs	50
Loss Contingency Accrual		$ 0

Number of pending claims pertaining to a loss contingency.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118942415&loc=d3e14435-108349

Name:	us-gaap_LossContingencyPendingClaimsNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant