Retirement And Employee Benefit Plans (Schedule Of Allocation Of Plan Assets) (Details) - Pension Benefits [Member]	12 Months Ended
	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations	100.00%
Actual asset allocations	100.00%
Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations	28.00%
Actual asset allocations	25.00%
Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations	2.00%
Actual asset allocations	5.00%
U.S. Equity [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations	35.00%
Actual asset allocations	36.00%
Non-U.S. Equity [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations	30.00%
Actual asset allocations	28.00%
Emerging Markets Equity [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations	5.00%
Actual asset allocations	6.00%
Opportunistic Securities [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations
Actual asset allocations