Distribution System Improvement Charge, Percent of Amount Billed to Customers

No definition available.

Name:	ugu_DistributionSystemImprovementChargePercentofAmountBilledtoCustomers
Namespace Prefix:	ugu_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum Period Post Petition to File General Rate Filing

+ References

No definition available.

+ Details

Name:	ugu_MaximumPeriodPostPetitiontoFileGeneralRateFiling
Namespace Prefix:	ugu_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Public Utilities, Requested Rate, Review Period

+ References

No definition available.

+ Details

Name:	ugu_PublicUtilitiesRequestedRateReviewPeriod
Namespace Prefix:	ugu_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair value of the assets less the liabilities of a derivative or group of derivatives.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 45
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=49121117&loc=d3e13433-108611

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=49121117&loc=d3e13495-108611

+ Details

Name:	us-gaap_DerivativeFairValueOfDerivativeNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of public utility's approved rate increase (decrease) by regulatory agency.

+ References

No definition available.

+ Details

Name:	us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of public utility's requested rate increase (decrease) with regulatory agency.

+ References

No definition available.

+ Details

Name:	us-gaap_PublicUtilitiesRequestedRateIncreaseDecreaseAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_RegulatoryAssetLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_RegulatoryAgencyAxis=ugu_PennsylvaniaPublicUtilityCommissionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=ugu_PNGMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=ugu_CPGMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RegulatoryAssetAxis=ugu_GasUtilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Regulatory Assets and Liabilities and Regulatory Matters - Narrative (Details) - USD ($) $ in Thousands					1 Months Ended	3 Months Ended	12 Months Ended
	Jan. 19, 2017	Oct. 14, 2016	Apr. 01, 2016	Apr. 01, 2015	Mar. 31, 2016	Dec. 31, 2016	Sep. 30, 2014	Sep. 30, 2016	Dec. 31, 2015
Pennsylvania PUC
Regulatory Assets
Operating revenue increase		$ 27,000
Maximum period post petition to file general rate filing (in years)						5 years
Pennsylvania PUC \| Maximum
Regulatory Assets
Distribution system improvement charge, percent of amount billed to customers					5.00%	5.00%	0.00%
Pennsylvania PUC \| Maximum \| PNG
Regulatory Assets
Distribution system improvement charge, percent of amount billed to customers				0.00%	10.00%
Pennsylvania PUC \| Maximum \| CPG
Regulatory Assets
Distribution system improvement charge, percent of amount billed to customers			0.00%		10.00%
Pennsylvania PUC \| Subsequent Event
Regulatory Assets
Requested operating revenue increase	$ 21,700
Requested rate change, review process period	9 months
Gas Utility
Regulatory Assets
Fair value of unrealized gains (losses)						$ 6,927		$ 4,263	$ (4,488)