Basis of Presentation and Recent Developments (Details) $ in Thousands	3 Months Ended
Mar. 31, 2019 USD ($)
Basis of Presentation and Recent Developments [Abstract]
Right-of-use asset	$ 6,700
Lease liability	7,100
Regulatory assets	$ 400

Discloses amount of embedded regulatory assets within the plant accounts. This may result when the regulatory depreciable life is longer than the depreciable life generally used for nonregulatory accounting.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 980
-SubTopic 340
-Section 25
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=77907324&loc=d3e43603-110378

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 980
-SubTopic 340
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 980
-SubTopic 20
-Section 40
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109242747&loc=d3e42004-110369

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