Retirement, Other Postretirement Benefits, And Defined Contribution Plans (Investments Held For Qualified Pension And Other Postretirement Plans Measured At Fair Value) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Accumulated Benefit Obligation	$ 7,800,000	$ 6,900,000
Investments	6,358,874	5,544,060
Cash	1,407	2,591
Other pending transactions	(22,549)	5,956
Less: Other postretirement assets included in total investments	(66,572)	(55,192)
Defined Benefit Plan, Plan Assets, Amount	6,271,160	5,497,415
Qualified Pension Plans [Member] | Interest Bearing Cash [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments		7,715
Qualified Pension Plans [Member] | Preferred [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	10,379	8,250
Qualified Pension Plans [Member] | Common Stock [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	857,159	695,003
Qualified Pension Plans [Member] | Common Collective Trusts [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	2,698,697	2,408,053
Qualified Pension Plans [Member] | U.S. Government securities [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	805,671	675,880
Qualified Pension Plans [Member] | Corporate Debt Securities [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	762,577	619,310
Qualified Pension Plans [Member] | Registered Investment Companies [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	132,389	108,740
Qualified Pension Plans [Member] | Registered Investment Companies [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	1,008,371	931,439
Qualified Pension Plans [Member] | Other [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	43,179	50,348
Qualified Pension Plans [Member] | Insurance Company General Account (Unallocated Contracts) [Member] | Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	40,452	39,322
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	618,045	553,353
Other pending transactions	1,645	1,237
Plus: Other postretirement assets included in the investments of the qualified pension trust	66,572	55,192
Defined Benefit Plan, Plan Assets, Amount	686,262	609,782	$ 659,327
Other Postretirement Benefits Plan [Member] | Common Collective Trusts [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	289,398	244,729
Other Postretirement Benefits Plan [Member] | U.S. Government securities [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	139,227	143,213
Other Postretirement Benefits Plan [Member] | Corporate Debt Securities [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	130,333	105,989
Other Postretirement Benefits Plan [Member] | Registered Investment Companies [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	1,877	2,442
Other Postretirement Benefits Plan [Member] | Other [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	57,210	56,980
Fair Value Inputs Level 1 [Member] | Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	1,053,842	843,233
Fair Value Inputs Level 1 [Member] | Qualified Pension Plans [Member] | Interest Bearing Cash [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments		0
Fair Value Inputs Level 1 [Member] | Qualified Pension Plans [Member] | Preferred [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	10,379	8,250
Fair Value Inputs Level 1 [Member] | Qualified Pension Plans [Member] | Common Stock [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	857,159	695,003
Fair Value Inputs Level 1 [Member] | Qualified Pension Plans [Member] | Common Collective Trusts [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments
Fair Value Inputs Level 1 [Member] | Qualified Pension Plans [Member] | U.S. Government securities [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	0	0
Fair Value Inputs Level 1 [Member] | Qualified Pension Plans [Member] | Corporate Debt Securities [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	0	0
Fair Value Inputs Level 1 [Member] | Qualified Pension Plans [Member] | Registered Investment Companies [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	132,389	108,740
Fair Value Inputs Level 1 [Member] | Qualified Pension Plans [Member] | Registered Investment Companies [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	53,842	29,374
Fair Value Inputs Level 1 [Member] | Qualified Pension Plans [Member] | Other [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	73	1,866
Fair Value Inputs Level 1 [Member] | Qualified Pension Plans [Member] | Insurance Company General Account (Unallocated Contracts) [Member] | Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	0	0
Fair Value Inputs Level 1 [Member] | Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	51,807	65,616
Fair Value Inputs Level 1 [Member] | Other Postretirement Benefits Plan [Member] | U.S. Government securities [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	49,930	63,174
Fair Value Inputs Level 1 [Member] | Other Postretirement Benefits Plan [Member] | Corporate Debt Securities [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	0	0
Fair Value Inputs Level 1 [Member] | Other Postretirement Benefits Plan [Member] | Registered Investment Companies [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	1,877	2,442
Fair Value Inputs Level 1 [Member] | Other Postretirement Benefits Plan [Member] | Other [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	0	0
Fair Value Inputs Level 2 [Member] | Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	1,654,709	1,393,406
Fair Value Inputs Level 2 [Member] | Qualified Pension Plans [Member] | Interest Bearing Cash [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments		7,715
Fair Value Inputs Level 2 [Member] | Qualified Pension Plans [Member] | Preferred [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	0	0
Fair Value Inputs Level 2 [Member] | Qualified Pension Plans [Member] | Common Stock [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	0	0
Fair Value Inputs Level 2 [Member] | Qualified Pension Plans [Member] | Common Collective Trusts [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments
Fair Value Inputs Level 2 [Member] | Qualified Pension Plans [Member] | U.S. Government securities [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	805,671	675,880
Fair Value Inputs Level 2 [Member] | Qualified Pension Plans [Member] | Corporate Debt Securities [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	762,577	619,310
Fair Value Inputs Level 2 [Member] | Qualified Pension Plans [Member] | Registered Investment Companies [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	0	0
Fair Value Inputs Level 2 [Member] | Qualified Pension Plans [Member] | Registered Investment Companies [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	2,903	2,697
Fair Value Inputs Level 2 [Member] | Qualified Pension Plans [Member] | Other [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	43,106	48,482
Fair Value Inputs Level 2 [Member] | Qualified Pension Plans [Member] | Insurance Company General Account (Unallocated Contracts) [Member] | Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	40,452	39,322
Fair Value Inputs Level 2 [Member] | Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	276,840	243,008
Fair Value Inputs Level 2 [Member] | Other Postretirement Benefits Plan [Member] | U.S. Government securities [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	89,297	80,039
Fair Value Inputs Level 2 [Member] | Other Postretirement Benefits Plan [Member] | Corporate Debt Securities [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	130,333	105,989
Fair Value Inputs Level 2 [Member] | Other Postretirement Benefits Plan [Member] | Registered Investment Companies [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	0	0
Fair Value Inputs Level 2 [Member] | Other Postretirement Benefits Plan [Member] | Other [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	57,210	56,980
Fair Value Inputs Level 3 [Member] | Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	0	0
Fair Value Inputs Level 3 [Member] | Qualified Pension Plans [Member] | Interest Bearing Cash [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments		0
Fair Value Inputs Level 3 [Member] | Qualified Pension Plans [Member] | Preferred [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	0	0
Fair Value Inputs Level 3 [Member] | Qualified Pension Plans [Member] | Common Stock [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	0	0
Fair Value Inputs Level 3 [Member] | Qualified Pension Plans [Member] | Common Collective Trusts [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments
Fair Value Inputs Level 3 [Member] | Qualified Pension Plans [Member] | U.S. Government securities [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	0	0
Fair Value Inputs Level 3 [Member] | Qualified Pension Plans [Member] | Corporate Debt Securities [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	0	0
Fair Value Inputs Level 3 [Member] | Qualified Pension Plans [Member] | Registered Investment Companies [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	0	0
Fair Value Inputs Level 3 [Member] | Qualified Pension Plans [Member] | Registered Investment Companies [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	0	0
Fair Value Inputs Level 3 [Member] | Qualified Pension Plans [Member] | Other [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	0	0
Fair Value Inputs Level 3 [Member] | Qualified Pension Plans [Member] | Insurance Company General Account (Unallocated Contracts) [Member] | Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	0	0
Fair Value Inputs Level 3 [Member] | Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	0	0
Fair Value Inputs Level 3 [Member] | Other Postretirement Benefits Plan [Member] | U.S. Government securities [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	0	0
Fair Value Inputs Level 3 [Member] | Other Postretirement Benefits Plan [Member] | Corporate Debt Securities [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	0	0
Fair Value Inputs Level 3 [Member] | Other Postretirement Benefits Plan [Member] | Registered Investment Companies [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	0	0
Fair Value Inputs Level 3 [Member] | Other Postretirement Benefits Plan [Member] | Other [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	$ 0	$ 0