Regulatory Assets and Liabilities Regulatory Assets and Liabilities Phantom (Details)	12 Months Ended
	Dec. 31, 2019
Revenue Subject to Refund
Regulatory Assets [Line Items]
Regulatory liability, remaining amortization period, minimum	1 year
Regulatory liability remaining amortization period, maximum	2 years
Conservation Programs
Regulatory Assets [Line Items]
Regulatory Asset Amortization Period, minimum	1 year
Regulatory Asset Amortization Period, maximum	2 years