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, 2016		Dec. 31, 2015		Dec. 31, 2014
Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments		$ 5,208,228		$ 4,744,032
Cash		929		373
Other pending transactions		8,869		1,124
Less: Other postretirement assets included in total investments		(46,824)		(38,096)
Total fair value of qualified pension assets		5,171,202		4,707,433
Qualified Pension Plans [Member] | Interest Bearing Cash [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments		3,610
Qualified Pension Plans [Member] | Preferred [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments		6,423		6,409
Qualified Pension Plans [Member] | Common Stock [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments		745,754		686,430
Qualified Pension Plans [Member] | Common Collective Trusts [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments		2,072,743		1,873,218
Qualified Pension Plans [Member] | 103-12 Investment Entities [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments		335,818		283,288
Qualified Pension Plans [Member] | U.S. Government securities [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments		370,681		345,684
Qualified Pension Plans [Member] | Corporate Debt Securities [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments		630,726		595,862
Qualified Pension Plans [Member] | Registered Investment Companies [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments		258,879		202,282
Qualified Pension Plans [Member] | Registered Investment Companies [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments		640,836		600,646
Qualified Pension Plans [Member] | Other [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments		105,647		114,215
Qualified Pension Plans [Member] | Insurance Company General Account (Unallocated Contracts) [Member] | Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments		37,111		35,998
Other Postretirement [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments		549,732		540,493
Other pending transactions		104		480
Plus: Other postretirement assets included in the investments of the qualified pension trust		46,824		38,096
Total fair value of qualified pension assets		596,660		579,069		$ 597,627
Other Postretirement [Member] | Common Collective Trusts [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments		368,704		348,604
Other Postretirement [Member] | U.S. Government securities [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments		73,729		76,011
Other Postretirement [Member] | Corporate Debt Securities [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments		58,787		62,629
Other Postretirement [Member] | Registered Investment Companies [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments		3,123		3,572
Other Postretirement [Member] | Other [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments		45,389		49,677
Fair Value Inputs Level 1 [Member] | Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments		1,046,403		950,343
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	[1]	6,423		6,409
Fair Value Inputs Level 1 [Member] | Qualified Pension Plans [Member] | Common Stock [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	[1]	745,715		686,335
Fair Value Inputs Level 1 [Member] | Qualified Pension Plans [Member] | Common Collective Trusts [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	[2]	0
Fair Value Inputs Level 1 [Member] | Qualified Pension Plans [Member] | 103-12 Investment Entities [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	[3]
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		136	[1]	1,879	[4]
Fair Value Inputs Level 1 [Member] | Qualified Pension Plans [Member] | Corporate Debt Securities [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	[4]	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		258,879	[5]	202,282	[6]
Fair Value Inputs Level 1 [Member] | Qualified Pension Plans [Member] | Registered Investment Companies [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments		35,216	[5]	53,438	[6]
Fair Value Inputs Level 1 [Member] | Qualified Pension Plans [Member] | Other [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	[7]	34		0
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	[8]	0		0
Fair Value Inputs Level 1 [Member] | Other Postretirement [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments		33,755		37,361
Fair Value Inputs Level 1 [Member] | Other Postretirement [Member] | U.S. Government securities [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	[1]	30,632		33,789
Fair Value Inputs Level 1 [Member] | Other Postretirement [Member] | Corporate Debt Securities [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	[4]	0		0
Fair Value Inputs Level 1 [Member] | Other Postretirement [Member] | Registered Investment Companies [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	[5]	3,123		3,572
Fair Value Inputs Level 1 [Member] | Other Postretirement [Member] | Other [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	[7]	0		0
Fair Value Inputs Level 2 [Member] | Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments		1,150,339		1,092,660
Fair Value Inputs Level 2 [Member] | Qualified Pension Plans [Member] | Interest Bearing Cash [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	[4]	3,610
Fair Value Inputs Level 2 [Member] | Qualified Pension Plans [Member] | Preferred [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	[4]	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		39		95
Fair Value Inputs Level 2 [Member] | Qualified Pension Plans [Member] | Common Collective Trusts [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	[2]	0
Fair Value Inputs Level 2 [Member] | Qualified Pension Plans [Member] | 103-12 Investment Entities [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	[3]
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	[4]	370,545		343,805
Fair Value Inputs Level 2 [Member] | Qualified Pension Plans [Member] | Corporate Debt Securities [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	[4]	630,726		595,862
Fair Value Inputs Level 2 [Member] | Qualified Pension Plans [Member] | Registered Investment Companies [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	[6]	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	[6]	2,695		2,685
Fair Value Inputs Level 2 [Member] | Qualified Pension Plans [Member] | Other [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	[7]	105,613		114,215
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	[8]	37,111		35,998
Fair Value Inputs Level 2 [Member] | Other Postretirement [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments		147,273		154,528
Fair Value Inputs Level 2 [Member] | Other Postretirement [Member] | U.S. Government securities [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	[4]	43,097		42,222
Fair Value Inputs Level 2 [Member] | Other Postretirement [Member] | Corporate Debt Securities [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	[4]	58,787		62,629
Fair Value Inputs Level 2 [Member] | Other Postretirement [Member] | Registered Investment Companies [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	[5]	0		0
Fair Value Inputs Level 2 [Member] | Other Postretirement [Member] | Other [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	[7]	45,389		49,677
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	[4]	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
Fair Value Inputs Level 3 [Member] | Qualified Pension Plans [Member] | Common Collective Trusts [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	[2]	0
Fair Value Inputs Level 3 [Member] | Qualified Pension Plans [Member] | 103-12 Investment Entities [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	[3]
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	[4]	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	[4]	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	[6]	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	[6]	0		0
Fair Value Inputs Level 3 [Member] | Qualified Pension Plans [Member] | Other [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	[7]	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	[8]	0		0
Fair Value Inputs Level 3 [Member] | Other Postretirement [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments		0		0
Fair Value Inputs Level 3 [Member] | Other Postretirement [Member] | U.S. Government securities [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	[4]	0		0
Fair Value Inputs Level 3 [Member] | Other Postretirement [Member] | Corporate Debt Securities [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	[4]	0		0
Fair Value Inputs Level 3 [Member] | Other Postretirement [Member] | Registered Investment Companies [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	[5]	0		0
Fair Value Inputs Level 3 [Member] | Other Postretirement [Member] | Other [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments	[7]	$ 0		$ 0

[1] (b)Common stocks, certain preferred stocks, and certain fixed income debt securities (government) are stated at fair value determined by quoted market prices.

[2] (c)The common collective trusts hold investments in accordance with stated objectives. The investment strategy of the trusts is to capture the growth potential of equity markets by replicating the performance of a specified index.

[3] (h)103-12 investment entities hold investments in accordance with stated objectives. The investment strategy of the investment entities is to capture the growth potential of international equity markets by replicating the performance of a specified index. 103-12 investment entities estimate fair value using net asset value as a practical expedient.

[4] (a)Certain preferred stocks and certain fixed income debt securities (corporate, government, and securitized) are stated at fair value as determined by broker quotes.

[5] (d)Registered investment companies are money market mutual funds with a stable net asset value of one dollar per share

[6] (f)

[7] The other remaining assets are U.S. municipal and foreign government bonds stated at fair value as determined by broker quotes.

[8] (g)The unallocated insurance contract investments are recorded at contract value, which approximates fair value. The contract value represents contributions made under the contract, plus interest, less funds used to pay benefits and contract expenses, and less distributions to the master trust.