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, 2018	Dec. 31, 2017	Dec. 31, 2016
Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Accumulated Benefit Obligation	$ 6,900,000	$ 7,400,000
Investments	5,544,060	6,122,808
Cash	2,591	1,508
Other pending transactions	5,956	5,179
Less: Other postretirement assets included in total investments	(55,192)	(58,179)
Defined Benefit Plan, Plan Assets, Amount	5,497,415	6,071,316
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	8,250	11,461
Qualified Pension Plans [Member] | Common Stock [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	695,003	663,957
Qualified Pension Plans [Member] | Common Collective Trusts [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	2,408,053	3,198,799
Qualified Pension Plans [Member] | U.S. Government securities [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	675,880	638,832
Qualified Pension Plans [Member] | Corporate Debt Securities [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	619,310	619,735
Qualified Pension Plans [Member] | Registered Investment Companies [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	108,740	125,174
Qualified Pension Plans [Member] | Registered Investment Companies [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	931,439	764,251
Qualified Pension Plans [Member] | Other [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	50,348	62,605
Qualified Pension Plans [Member] | Insurance Company General Account (Unallocated Contracts) [Member] | Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	39,322	37,994
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	553,353	600,154
Other pending transactions	1,237	994
Plus: Other postretirement assets included in the investments of the qualified pension trust	55,192	58,179
Defined Benefit Plan, Plan Assets, Amount	609,782	659,327	$ 596,660
Other Postretirement Benefits Plan [Member] | Common Collective Trusts [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	244,729	300,139
Other Postretirement Benefits Plan [Member] | U.S. Government securities [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	143,213	158,392
Other Postretirement Benefits Plan [Member] | Corporate Debt Securities [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	105,989	92,869
Other Postretirement Benefits Plan [Member] | Registered Investment Companies [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	2,442	3,127
Other Postretirement Benefits Plan [Member] | Other [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	56,980	45,627
Fair Value Inputs Level 1 [Member] | Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	843,233	846,372
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	8,250	11,461
Fair Value Inputs Level 1 [Member] | Qualified Pension Plans [Member] | Common Stock [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	695,003	663,923
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	108,740	125,174
Fair Value Inputs Level 1 [Member] | Qualified Pension Plans [Member] | Registered Investment Companies [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	29,374	45,768
Fair Value Inputs Level 1 [Member] | Qualified Pension Plans [Member] | Other [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	1,866	46
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	65,616	84,729
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	63,174	81,602
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	2,442	3,127
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	1,393,406	1,361,889
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	34
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	675,880	638,832
Fair Value Inputs Level 2 [Member] | Qualified Pension Plans [Member] | Corporate Debt Securities [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	619,310	619,735
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	2,697	2,735
Fair Value Inputs Level 2 [Member] | Qualified Pension Plans [Member] | Other [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	48,482	62,559
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	39,322	37,994
Fair Value Inputs Level 2 [Member] | Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	243,008	215,286
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	80,039	76,790
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	105,989	92,869
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	56,980	45,627
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