Accounting For Income Taxes (Schedule Of Components Of Income Tax Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Components of Income Tax Expense (Benefit) [Line Items]
Current income tax expense (benefit)	$ 12,212	$ (67,059)	$ 37,743
Deferred income tax expense	51,801	144,269	23,532
Total income tax expense	67,449	72,240	58,014
Utility and Other (Excluding Ecova) [Member]
Components of Income Tax Expense (Benefit) [Line Items]
Deferred income tax expense	$ 55,237	$ 139,299	$ 20,271