Benefit Plans (Fair Value of Plan Assets Measured on a Recurring Basis) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Corporate and other bonds [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	$ 520	$ 447
Corporate and other bonds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets
Corporate and other bonds [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	505	436
Corporate and other bonds [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	15	11	10
States, municipalities and political subdivisions [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	73	91
States, municipalities and political subdivisions [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets
States, municipalities and political subdivisions [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	73	91
States, municipalities and political subdivisions [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets
Residential mortgage-backed [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	130	161
Residential mortgage-backed [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets
Residential mortgage-backed [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	130	161
Residential mortgage-backed [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets
Commercial Mortgage Backed Securities [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	106	105
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	106	105
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets
Other asset-backed [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	12
Other asset-backed [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets
Other asset-backed [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	12
Other asset-backed [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets
Total asset-backed [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	248	266
Total asset-backed [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets
Total asset-backed [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	248	266
Total asset-backed [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets
Fixed Maturities [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	841	804
Fixed Maturities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets
Fixed Maturities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	826	793
Fixed Maturities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	15	11	10
Equity securities [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	605	493
Equity securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	480	386
Equity securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	117	102
Equity securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	8	5	5
Derivative Financial Instruments, Assets [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	2	1
Derivative Financial Instruments, Assets [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	2	1
Derivative Financial Instruments, Assets [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets
Derivative Financial Instruments, Assets [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets
Short-term Investments [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	94	119
Short-term Investments [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	45	37
Short-term Investments [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	49	82
Short-term Investments [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets
Hedge Funds [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	969	896
Hedge Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets
Hedge Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	647	537
Hedge Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	322	359	330
Private Equity Funds [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	114	62
Private Equity Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets
Private Equity Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets
Private Equity Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	114	62	65
Total limited partnerships [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	1,083	958
Total limited partnerships [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets
Total limited partnerships [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	647	537
Total limited partnerships [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	436	421	395
Other Assets [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	31	40
Other Assets [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets
Other Assets [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	31	40
Other Assets [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets
Investment Contracts with Insurance Company [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets		10
Investment Contracts with Insurance Company [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets
Investment Contracts with Insurance Company [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets
Investment Contracts with Insurance Company [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets		10	10
Total assets [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	2,656	2,425
Total assets [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	527	424
Total assets [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	1,670	1,554
Total assets [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan disclosure [Line items]
Fair value of plan assets	$ 459	$ 447	$ 420