Retirement Plans (Fair Value Of Plan Assets By Investment Category And The Corresponding Level Within The Fair Value Hierarchy) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2012	Dec. 31, 2013
Compensation And Retirement Disclosure Line Items
Maximum equity holding percentage of total fair value	1.00%		1.00%
Significant Unobservable Inputs (Level 3)
Compensation And Retirement Disclosure Line Items
Total pension plan assets	446		249	$ 343
Significant Unobservable Inputs (Level 3) | Real Estate Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	139		32	34
Significant Unobservable Inputs (Level 3) | Hedge Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	195		101	184
Significant Unobservable Inputs (Level 3) | Insurance Deposit Agreements
Compensation And Retirement Disclosure Line Items
Total pension plan assets	103		108	115
Significant Unobservable Inputs (Level 3) | Private Equity Investments
Compensation And Retirement Disclosure Line Items
Total pension plan assets	9		8	10
Pension Benefits
Compensation And Retirement Disclosure Line Items
Total pension plan assets	9,084			8,476
Pension Benefits | Equity Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	4,272			3,935
Pension Benefits | Money Market Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	49			97
Pension Benefits | Fixed Income Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	296			303
Pension Benefits | Real Estate Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	139			34
Pension Benefits | Commodity Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	6			8
Pension Benefits | Hedge Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	510			471
Pension Benefits | Insurance Deposit Agreements
Compensation And Retirement Disclosure Line Items
Total pension plan assets	103			115
Pension Benefits | U.S. Companies
Compensation And Retirement Disclosure Line Items
Total pension plan assets	775	[1]		685	[1]
Pension Benefits | International Companies
Compensation And Retirement Disclosure Line Items
Total pension plan assets	90			128
Pension Benefits | Private Equity Investments
Compensation And Retirement Disclosure Line Items
Total pension plan assets	9			10
Pension Benefits | Quoted Prices in Active Markets for Identical Assets (Level 1)
Compensation And Retirement Disclosure Line Items
Total pension plan assets	897			848
Pension Benefits | Quoted Prices in Active Markets for Identical Assets (Level 1) | Equity Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	0			0
Pension Benefits | Quoted Prices in Active Markets for Identical Assets (Level 1) | Money Market Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	0			0
Pension Benefits | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fixed Income Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	0			0
Pension Benefits | Quoted Prices in Active Markets for Identical Assets (Level 1) | Real Estate Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	0			0
Pension Benefits | Quoted Prices in Active Markets for Identical Assets (Level 1) | Commodity Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	0			0
Pension Benefits | Quoted Prices in Active Markets for Identical Assets (Level 1) | Hedge Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	0			0
Pension Benefits | Quoted Prices in Active Markets for Identical Assets (Level 1) | Insurance Deposit Agreements
Compensation And Retirement Disclosure Line Items
Total pension plan assets	0			0
Pension Benefits | Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Companies
Compensation And Retirement Disclosure Line Items
Total pension plan assets	775	[1]		685	[1]
Pension Benefits | Quoted Prices in Active Markets for Identical Assets (Level 1) | International Companies
Compensation And Retirement Disclosure Line Items
Total pension plan assets	90			128
Pension Benefits | Quoted Prices in Active Markets for Identical Assets (Level 1) | Private Equity Investments
Compensation And Retirement Disclosure Line Items
Total pension plan assets	0			0
Pension Benefits | Significant Other Observable Inputs (Level 2)
Compensation And Retirement Disclosure Line Items
Total pension plan assets	7,742			7,286
Pension Benefits | Significant Other Observable Inputs (Level 2) | Equity Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	4,272			3,935
Pension Benefits | Significant Other Observable Inputs (Level 2) | Money Market Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	49			97
Pension Benefits | Significant Other Observable Inputs (Level 2) | Fixed Income Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	296			303
Pension Benefits | Significant Other Observable Inputs (Level 2) | Real Estate Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	0			0
Pension Benefits | Significant Other Observable Inputs (Level 2) | Commodity Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	6			8
Pension Benefits | Significant Other Observable Inputs (Level 2) | Hedge Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	316			288
Pension Benefits | Significant Other Observable Inputs (Level 2) | Insurance Deposit Agreements
Compensation And Retirement Disclosure Line Items
Total pension plan assets	0			0
Pension Benefits | Significant Other Observable Inputs (Level 2) | U.S. Companies
Compensation And Retirement Disclosure Line Items
Total pension plan assets	0	[1]		0	[1]
Pension Benefits | Significant Other Observable Inputs (Level 2) | International Companies
Compensation And Retirement Disclosure Line Items
Total pension plan assets	0			0
Pension Benefits | Significant Other Observable Inputs (Level 2) | Private Equity Investments
Compensation And Retirement Disclosure Line Items
Total pension plan assets	0			0
Pension Benefits | Significant Unobservable Inputs (Level 3)
Compensation And Retirement Disclosure Line Items
Total pension plan assets	445			342
Pension Benefits | Significant Unobservable Inputs (Level 3) | Equity Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	0			0
Pension Benefits | Significant Unobservable Inputs (Level 3) | Money Market Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	0			0
Pension Benefits | Significant Unobservable Inputs (Level 3) | Fixed Income Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	0			0
Pension Benefits | Significant Unobservable Inputs (Level 3) | Real Estate Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	139			34
Pension Benefits | Significant Unobservable Inputs (Level 3) | Commodity Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	0			0
Pension Benefits | Significant Unobservable Inputs (Level 3) | Hedge Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	194			183
Pension Benefits | Significant Unobservable Inputs (Level 3) | Insurance Deposit Agreements
Compensation And Retirement Disclosure Line Items
Total pension plan assets	103			115
Pension Benefits | Significant Unobservable Inputs (Level 3) | U.S. Companies
Compensation And Retirement Disclosure Line Items
Total pension plan assets	0	[1]		0	[1]
Pension Benefits | Significant Unobservable Inputs (Level 3) | International Companies
Compensation And Retirement Disclosure Line Items
Total pension plan assets	0			0
Pension Benefits | Significant Unobservable Inputs (Level 3) | Private Equity Investments
Compensation And Retirement Disclosure Line Items
Total pension plan assets	9			10
Pension Benefits | Cash
Compensation And Retirement Disclosure Line Items
Total pension plan assets	32			35
Pension Benefits | Cash | Quoted Prices in Active Markets for Identical Assets (Level 1)
Compensation And Retirement Disclosure Line Items
Total pension plan assets	32			35
Pension Benefits | Cash | Significant Other Observable Inputs (Level 2)
Compensation And Retirement Disclosure Line Items
Total pension plan assets	0			0
Pension Benefits | Cash | Significant Unobservable Inputs (Level 3)
Compensation And Retirement Disclosure Line Items
Total pension plan assets	0			0
Pension Benefits | Treasury Securities
Compensation And Retirement Disclosure Line Items
Total pension plan assets	449			428
Pension Benefits | Treasury Securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Compensation And Retirement Disclosure Line Items
Total pension plan assets	0			0
Pension Benefits | Treasury Securities | Significant Other Observable Inputs (Level 2)
Compensation And Retirement Disclosure Line Items
Total pension plan assets	449			428
Pension Benefits | Treasury Securities | Significant Unobservable Inputs (Level 3)
Compensation And Retirement Disclosure Line Items
Total pension plan assets	0			0
Pension Benefits | Corporate Bonds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	2,354	[2]		2,227	[2]
Pension Benefits | Corporate Bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Compensation And Retirement Disclosure Line Items
Total pension plan assets	0	[2]		0	[2]
Pension Benefits | Corporate Bonds | Significant Other Observable Inputs (Level 2)
Compensation And Retirement Disclosure Line Items
Total pension plan assets	2,354	[2]		2,227	[2]
Pension Benefits | Corporate Bonds | Significant Unobservable Inputs (Level 3)
Compensation And Retirement Disclosure Line Items
Total pension plan assets	0	[2]		0	[2]
Other Postretirement Benefit Plans, Defined Benefit
Compensation And Retirement Disclosure Line Items
Total pension plan assets	553			519
Other Postretirement Benefit Plans, Defined Benefit | Hedge Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	2			2
Other Postretirement Benefit Plans, Defined Benefit | Quoted Prices in Active Markets for Identical Assets (Level 1)
Compensation And Retirement Disclosure Line Items
Total pension plan assets	181			166
Other Postretirement Benefit Plans, Defined Benefit | Quoted Prices in Active Markets for Identical Assets (Level 1) | Hedge Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	0			0
Other Postretirement Benefit Plans, Defined Benefit | Significant Other Observable Inputs (Level 2)
Compensation And Retirement Disclosure Line Items
Total pension plan assets	371			352
Other Postretirement Benefit Plans, Defined Benefit | Significant Other Observable Inputs (Level 2) | Hedge Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	1			1
Other Postretirement Benefit Plans, Defined Benefit | Significant Unobservable Inputs (Level 3)
Compensation And Retirement Disclosure Line Items
Total pension plan assets	1			1
Other Postretirement Benefit Plans, Defined Benefit | Significant Unobservable Inputs (Level 3) | Hedge Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	1			1
Other Postretirement Benefit Plans, Defined Benefit | Cash
Compensation And Retirement Disclosure Line Items
Total pension plan assets	3			6
Other Postretirement Benefit Plans, Defined Benefit | Cash | Quoted Prices in Active Markets for Identical Assets (Level 1)
Compensation And Retirement Disclosure Line Items
Total pension plan assets	3			6
Other Postretirement Benefit Plans, Defined Benefit | Cash | Significant Other Observable Inputs (Level 2)
Compensation And Retirement Disclosure Line Items
Total pension plan assets	0			0
Other Postretirement Benefit Plans, Defined Benefit | Cash | Significant Unobservable Inputs (Level 3)
Compensation And Retirement Disclosure Line Items
Total pension plan assets	0			0
Equity Securities [Member] | Other Postretirement Benefit Plans, Defined Benefit
Compensation And Retirement Disclosure Line Items
Total pension plan assets	167			154
Equity Securities [Member] | Other Postretirement Benefit Plans, Defined Benefit | Quoted Prices in Active Markets for Identical Assets (Level 1)
Compensation And Retirement Disclosure Line Items
Total pension plan assets	167			154
Equity Securities [Member] | Other Postretirement Benefit Plans, Defined Benefit | Significant Other Observable Inputs (Level 2)
Compensation And Retirement Disclosure Line Items
Total pension plan assets	0			0
Equity Securities [Member] | Other Postretirement Benefit Plans, Defined Benefit | Significant Unobservable Inputs (Level 3)
Compensation And Retirement Disclosure Line Items
Total pension plan assets	0			0
Fixed Income Securities [Member] | Other Postretirement Benefit Plans, Defined Benefit
Compensation And Retirement Disclosure Line Items
Total pension plan assets	11			55
Fixed Income Securities [Member] | Other Postretirement Benefit Plans, Defined Benefit | Quoted Prices in Active Markets for Identical Assets (Level 1)
Compensation And Retirement Disclosure Line Items
Total pension plan assets	0			0
Fixed Income Securities [Member] | Other Postretirement Benefit Plans, Defined Benefit | Significant Other Observable Inputs (Level 2)
Compensation And Retirement Disclosure Line Items
Total pension plan assets	11			55
Fixed Income Securities [Member] | Other Postretirement Benefit Plans, Defined Benefit | Significant Unobservable Inputs (Level 3)
Compensation And Retirement Disclosure Line Items
Total pension plan assets	0			0
Comingled Funds [Member] | Other Postretirement Benefit Plans, Defined Benefit | Equity Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	314			296
Comingled Funds [Member] | Other Postretirement Benefit Plans, Defined Benefit | Fixed Income Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	56			6
Comingled Funds [Member] | Other Postretirement Benefit Plans, Defined Benefit | Quoted Prices in Active Markets for Identical Assets (Level 1) | Equity Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	5			0
Comingled Funds [Member] | Other Postretirement Benefit Plans, Defined Benefit | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fixed Income Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	6			6
Comingled Funds [Member] | Other Postretirement Benefit Plans, Defined Benefit | Significant Other Observable Inputs (Level 2) | Equity Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	309			296
Comingled Funds [Member] | Other Postretirement Benefit Plans, Defined Benefit | Significant Other Observable Inputs (Level 2) | Fixed Income Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	50			0
Comingled Funds [Member] | Other Postretirement Benefit Plans, Defined Benefit | Significant Unobservable Inputs (Level 3) | Equity Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	0			0
Comingled Funds [Member] | Other Postretirement Benefit Plans, Defined Benefit | Significant Unobservable Inputs (Level 3) | Fixed Income Funds
Compensation And Retirement Disclosure Line Items
Total pension plan assets	0			$ 0

[1] No single equity holding amounted to more than 1 percent of the total fair value.

[2] Our corporate bond investments had an average rating of A-.