Income Taxes (Details) - USD ($)	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Tax Audits [Abstract]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	21.00%
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent	2.10%	2.40%
Effective Income Tax Rate Reconciliation, Other Regulatory Items, Percent	(4.80%)	(4.40%)
Effective Income Tax Rate Reconciliation, Prior Year Income Taxes, Percent	(0.70%)	(0.20%)
Regulatory differences - reversal of prior quarters' ARAM deferral (b)	(0.60%)	(0.80%)
Effective Income Tax Rate Reconciliation, Tax Credit, Amount	(0.20%)	0.00%
Effective Income Tax Rate Reconciliation, Other Adjustments, Percent	(0.40%)	0.40%
Effective Income Tax Rate Reconciliation, Percent	16.40%	18.40%
Unrecognized Tax Benefits [Abstract]
Unrecognized tax benefit - Permanent tax positions	$ 3,300,000		$ 3,000,000.0
Unrecognized tax benefit - Temporary tax positions	1,500,000		1,500,000
Total unrecognized tax benefit	4,800,000		4,500,000
NOL and tax credit carryforwards	(4,100,000)		(3,800,000)
Net Deferred Tax Liability associated with the Unrecognized Tax Benefit Amounts and Related NOLs and Tax Credit Carryforwards	(1,100,000)		(800,000)
Upper bound of decrease in unrecognized tax benefit that is reasonably possible	3,600,000
Amounts accrued for penalties related to unrecognized tax benefits	0		$ 0
Internal Revenue Service (IRS)
Tax Audits [Abstract]
Potential Tax Adjustments	$ 0