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- Definition

Regulated Utlity, After-tax Allowed Rate of Return on Net Regulatory Assets and Liabilities

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Regulation and Rates [Line Items]

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- Definition

Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (b)
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Amount of revenue recognized that was previously reported as deferred or unearned revenue.

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- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (h)
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 20
-Section 45
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109238882&loc=d3e38679-109324

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

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

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

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

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

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

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Regulation and Rates Rate Adjustments (Details) - USD ($)							6 Months Ended	12 Months Ended
	Mar. 01, 2019	Nov. 07, 2018	May 01, 2018	Mar. 01, 2018	Dec. 19, 2017	Dec. 18, 2017	Dec. 31, 2013	Apr. 30, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Regulation and Rates [Line Items]
Income tax (benefit) expense									$ 30,092,000	$ 255,143,000	$ 140,204,000
Decoupling Mechanism [Member]
Regulation and Rates [Line Items]
Deferred Revenue, Revenue Recognized									20,800,000
Subsidiaries [Member]
Regulation and Rates [Line Items]
Income tax (benefit) expense			$ 34,600,000						50,700,000	$ 211,986,000	$ 175,347,000
Regulated Utility, Allowed Rate of Return on Net Regulatory Assets and Liabilities		7.49%			7.60%		7.77%
Subsidiaries [Member] \| Expedited Rate Filing (ERF) [Member] \| Electricity, US Regulated [Member]
Regulation and Rates [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount		$ 18,900,000
Public Utilities, Requested Rate Increase (Decrease), Percentage		0.90%
Subsidiaries [Member] \| Expedited Rate Filing (ERF) [Member] \| Natural Gas, US Regulated [Member]
Regulation and Rates [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount				$ 25,900,000
Public Utilities, Requested Rate Increase (Decrease), Amount		$ 21,700,000		$ 6,100,000
Public Utilities, Requested Rate Increase (Decrease), Percentage		2.70%
Subsidiaries [Member] \| Decoupling Mechanism [Member] \| Electricity, US Regulated [Member]
Regulation and Rates [Line Items]
Contract with Customer, Liability, Revenue Recognized									$ 800,000
Subsidiaries [Member] \| General Rate Case [Member]
Regulation and Rates [Line Items]
Regulated Utility, After-tax Allowed Rate of Return on Net Regulatory Assets and Liabilities					6.55%
Subsidiaries [Member] \| General Rate Case [Member] \| Electricity, US Regulated [Member]
Regulation and Rates [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Percentage					0.90%
Public Utilities, Approved Rate Increase (Decrease), Amount					$ 20,200,000
Subsidiaries [Member] \| General Rate Case [Member] \| Natural Gas, US Regulated [Member]
Regulation and Rates [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Percentage					(3.80%)
Public Utilities, Approved Rate Increase (Decrease), Amount					$ (35,500,000)
Maximum \| Subsidiaries [Member] \| Decoupling Mechanism [Member] \| Electricity, US Regulated [Member]
Regulation and Rates [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Percentage					3.00%
Maximum \| Subsidiaries [Member] \| Decoupling Mechanism [Member] \| Natural Gas, US Regulated [Member]
Regulation and Rates [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Percentage					5.00%	3.00%
Scenario, Forecast [Member] \| Subsidiaries [Member] \| Expedited Rate Filing (ERF) [Member] \| Electricity, US Regulated [Member]
Regulation and Rates [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount	$ 0
Scenario, Forecast [Member] \| Subsidiaries [Member] \| Expedited Rate Filing (ERF) [Member] \| Natural Gas, US Regulated [Member]
Regulation and Rates [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount	$ 21,500,000
Scenario, Forecast [Member] \| Subsidiaries [Member] \| Tax Cuts and Jobs Act [Member] \| Electricity, US Regulated [Member]
Regulation and Rates [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amended, Percentage								(3.40%)
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount								$ (72,900,000)
Scenario, Forecast [Member] \| Subsidiaries [Member] \| Tax Cuts and Jobs Act [Member] \| Natural Gas, US Regulated [Member]
Regulation and Rates [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amended, Percentage								(2.70%)
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount								$ (23,600,000)