Employee Retirement Benefits (Fair Value Hierarchy Of Assets Measured At Fair Value On A Recurring Basis) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Schedule of Pension and Other Postretirment Plan Assets by Fair Value
Available for sale securities, debt securities	$ 9,460	$ 9,121
Available for sale securities, equity securities	4,858	4,375
Fixed Maturities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value
Available for sale securities, debt securities	52	53
Fixed Maturities | States, Municipalities and Political Subdivisions
Schedule of Pension and Other Postretirment Plan Assets by Fair Value
Available for sale securities, debt securities	33	32
Fixed Maturities | Corporate Fixed Maturities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value
Available for sale securities, debt securities	19	21
Equity Securities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value
Available for sale securities, equity securities	277	261
Equity Securities | Common Stock
Schedule of Pension and Other Postretirment Plan Assets by Fair Value
Available for sale securities, equity securities	225	208
Level 1 | Fixed Maturities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value
Available for sale securities, debt securities	0	0
Level 1 | Fixed Maturities | States, Municipalities and Political Subdivisions
Schedule of Pension and Other Postretirment Plan Assets by Fair Value
Available for sale securities, debt securities	0	0
Level 1 | Fixed Maturities | Corporate Fixed Maturities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value
Available for sale securities, debt securities	0	0
Level 1 | Equity Securities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value
Available for sale securities, equity securities	225	208
Level 1 | Equity Securities | Common Stock
Schedule of Pension and Other Postretirment Plan Assets by Fair Value
Available for sale securities, equity securities	225	208
Level 2
Schedule of Pension and Other Postretirment Plan Assets by Fair Value
Available for sale securities, equity securities		53
Level 2 | Fixed Maturities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value
Available for sale securities, debt securities	52	53
Level 2 | Fixed Maturities | States, Municipalities and Political Subdivisions
Schedule of Pension and Other Postretirment Plan Assets by Fair Value
Available for sale securities, debt securities	33	32
Level 2 | Fixed Maturities | Corporate Fixed Maturities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value
Available for sale securities, debt securities	19	21
Level 2 | Equity Securities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value
Available for sale securities, equity securities	52
Level 2 | Equity Securities | Common Stock
Schedule of Pension and Other Postretirment Plan Assets by Fair Value
Available for sale securities, equity securities	0	0
Level 3
Schedule of Pension and Other Postretirment Plan Assets by Fair Value
Available for sale securities, equity securities		0
Level 3 | Fixed Maturities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value
Available for sale securities, debt securities	0	0
Level 3 | Fixed Maturities | States, Municipalities and Political Subdivisions
Schedule of Pension and Other Postretirment Plan Assets by Fair Value
Available for sale securities, debt securities	0	0
Level 3 | Fixed Maturities | Corporate Fixed Maturities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value
Available for sale securities, debt securities	0	0
Level 3 | Equity Securities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value
Available for sale securities, equity securities	0
Level 3 | Equity Securities | Common Stock
Schedule of Pension and Other Postretirment Plan Assets by Fair Value
Available for sale securities, equity securities	$ 0	$ 0