Summary Of Significant Accounting Policies Summary of Significant Accounting Policies (Effective Income Tax Rate) (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Accounting Policies [Abstract]
Effective Income Tax Rate	16.90%	37.50%
Federal Statutory Income Tax Rate			21.00%	35.00%
Income Tax Reconciliation, Amortization of Excess Deferred Income Taxes Associated with Utility Plant, Percent	6.40%		3.10%
Income Tax Reconciliation Settlement of Share Based Compensation Percent			1.00%