Pension Plans And Other Postretirement Benefit Plans (Changes In Level 3 Assets) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	37.00%	27.00%
Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	45.00%	58.00%
Other Post-Retirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets as of beginning of year	$ 30,868	$ 31,312
Fair value of plan assets as of end of year	33,365	30,868
Other Post-Retirement Benefits [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets as of beginning of year	0
Fair value of plan assets as of end of year	$ 0	$ 0
Other Post-Retirement Benefits [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	60.00%	60.00%
Other Post-Retirement Benefits [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	40.00%	40.00%
Pension Plan And SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets as of beginning of year	$ 517,234	$ 539,311
Fair value of plan assets as of end of year	540,914	517,234
Pension Plan And SERP [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets as of beginning of year	0
Fair value of plan assets as of end of year	0	0
Pension Plan And SERP [Member] | Absolute Return [Member] | Partnership And Closely Held Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets as of beginning of year	38,302
Fair value of plan assets as of end of year	39,077	38,302
Pension Plan And SERP [Member] | Real Estate [Member] | Common/Collective Trusts [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets as of beginning of year	24,147
Fair value of plan assets as of end of year	19,779	24,147
Pension Plan And SERP [Member] | Real Estate [Member] | Partnership And Closely Held Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets as of beginning of year	9,941
Fair value of plan assets as of end of year	7,649	9,941
Pension Plan And SERP [Member] | Private Equity Funds [Member] | Partnership And Closely Held Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets as of beginning of year	73
Fair value of plan assets as of end of year	$ 72	$ 73