Benefit Plans (Allocation Of Plan Assets) (Details)	Dec. 31, 2019
Pension Plans, Defined Benefit [Member] | Cash and equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual allocation, percentage	5.00%
Pension Plans, Defined Benefit [Member] | Equity securites - U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual allocation, percentage	25.00%
Pension Plans, Defined Benefit [Member] | Equity securities - international [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual allocation, percentage	22.00%
Pension Plans, Defined Benefit [Member] | Global asset securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual allocation, percentage	9.00%
Pension Plans, Defined Benefit [Member] | Risk parity securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual allocation, percentage	10.00%
Pension Plans, Defined Benefit [Member] | Fixed income securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual allocation, percentage	29.00%
Other Postretirement Benefits Plans [Member] | Cash and equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual allocation, percentage	3.00%
Other Postretirement Benefits Plans [Member] | Equity securites - U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual allocation, percentage	25.00%
Other Postretirement Benefits Plans [Member] | Equity securities - international [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual allocation, percentage	2.00%
Other Postretirement Benefits Plans [Member] | Fixed income securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual allocation, percentage	70.00%
Minimum [Member] | Pension Plans, Defined Benefit [Member] | Cash and equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Target range allocation, percentage	0.00%
Minimum [Member] | Pension Plans, Defined Benefit [Member] | Equity securites - U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Target range allocation, percentage	6.00%
Minimum [Member] | Pension Plans, Defined Benefit [Member] | Equity securities - international [Member]
Defined Benefit Plan Disclosure [Line Items]
Target range allocation, percentage	14.00%
Minimum [Member] | Pension Plans, Defined Benefit [Member] | Global asset securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target range allocation, percentage	5.00%
Minimum [Member] | Pension Plans, Defined Benefit [Member] | Risk parity securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target range allocation, percentage	5.00%
Minimum [Member] | Pension Plans, Defined Benefit [Member] | Fixed income securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target range allocation, percentage	20.00%
Minimum [Member] | Other Postretirement Benefits Plans [Member] | Cash and equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Target range allocation, percentage	0.00%
Minimum [Member] | Other Postretirement Benefits Plans [Member] | Equity securites - U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Target range allocation, percentage	0.00%
Minimum [Member] | Other Postretirement Benefits Plans [Member] | Equity securities - international [Member]
Defined Benefit Plan Disclosure [Line Items]
Target range allocation, percentage	0.00%
Minimum [Member] | Other Postretirement Benefits Plans [Member] | Fixed income securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target range allocation, percentage	20.00%
Maximum [Member] | Pension Plans, Defined Benefit [Member] | Cash and equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Target range allocation, percentage	5.00%
Maximum [Member] | Pension Plans, Defined Benefit [Member] | Equity securites - U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Target range allocation, percentage	56.00%
Maximum [Member] | Pension Plans, Defined Benefit [Member] | Equity securities - international [Member]
Defined Benefit Plan Disclosure [Line Items]
Target range allocation, percentage	34.00%
Maximum [Member] | Pension Plans, Defined Benefit [Member] | Global asset securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target range allocation, percentage	15.00%
Maximum [Member] | Pension Plans, Defined Benefit [Member] | Risk parity securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target range allocation, percentage	15.00%
Maximum [Member] | Pension Plans, Defined Benefit [Member] | Fixed income securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target range allocation, percentage	40.00%
Maximum [Member] | Other Postretirement Benefits Plans [Member] | Cash and equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Target range allocation, percentage	5.00%
Maximum [Member] | Other Postretirement Benefits Plans [Member] | Equity securites - U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Target range allocation, percentage	46.00%
Maximum [Member] | Other Postretirement Benefits Plans [Member] | Equity securities - international [Member]
Defined Benefit Plan Disclosure [Line Items]
Target range allocation, percentage	34.00%
Maximum [Member] | Other Postretirement Benefits Plans [Member] | Fixed income securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target range allocation, percentage	100.00%