Benefit Plans (Fair Values of Pension Plan Assets) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	$ 7,077	$ 6,167
Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	1,823	1,212
Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	5,239	4,941
Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	15	14
Common/Collective Trusts [Member] | U.S. large cap [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	1,971	1,566
Common/Collective Trusts [Member] | U.S. large cap [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	0	0
Common/Collective Trusts [Member] | U.S. large cap [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	1,971	1,566
Common/Collective Trusts [Member] | U.S. large cap [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	0	0
Common/Collective Trusts [Member] | U.S. small cap [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	546	499
Common/Collective Trusts [Member] | U.S. small cap [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	0	0
Common/Collective Trusts [Member] | U.S. small cap [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	546	499
Common/Collective Trusts [Member] | U.S. small cap [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	0	0
Common/Collective Trusts [Member] | International developed markets [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	159	179
Common/Collective Trusts [Member] | International developed markets [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	0	0
Common/Collective Trusts [Member] | International developed markets [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	159	179
Common/Collective Trusts [Member] | International developed markets [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	0	0
Common/Collective Trusts [Member] | Long duration fixed income [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value		494
Common/Collective Trusts [Member] | Long duration fixed income [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value		0
Common/Collective Trusts [Member] | Long duration fixed income [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value		494
Common/Collective Trusts [Member] | Long duration fixed income [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value		0
U.S. And Foreign Government Securities Or Their Agencies [Member] | U.S. government and agencies [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	226	625
U.S. And Foreign Government Securities Or Their Agencies [Member] | U.S. government and agencies [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	0	0
U.S. And Foreign Government Securities Or Their Agencies [Member] | U.S. government and agencies [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	226	625
U.S. And Foreign Government Securities Or Their Agencies [Member] | U.S. government and agencies [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	0	0
U.S. And Foreign Government Securities Or Their Agencies [Member] | U.S. municipal bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	127	71
U.S. And Foreign Government Securities Or Their Agencies [Member] | U.S. municipal bonds [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	0	0
U.S. And Foreign Government Securities Or Their Agencies [Member] | U.S. municipal bonds [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	127	71
U.S. And Foreign Government Securities Or Their Agencies [Member] | U.S. municipal bonds [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	0	0
U.S. And Foreign Government Securities Or Their Agencies [Member] | Foreign government and agencies [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	275	311
U.S. And Foreign Government Securities Or Their Agencies [Member] | Foreign government and agencies [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	0	0
U.S. And Foreign Government Securities Or Their Agencies [Member] | Foreign government and agencies [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	275	311
U.S. And Foreign Government Securities Or Their Agencies [Member] | Foreign government and agencies [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	0	0
Equity Securities [Member] | International equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	1,051	759
Equity Securities [Member] | International equities [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	1,050	759
Equity Securities [Member] | International equities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	0	0
Equity Securities [Member] | International equities [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	1	0
Equity Securities [Member] | U.S. equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	506	300
Equity Securities [Member] | U.S. equities [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	506	300
Equity Securities [Member] | U.S. equities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	0	0
Equity Securities [Member] | U.S. equities [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	0	0
Registered Investment Companies [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	296	178
Registered Investment Companies [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	159	128
Registered Investment Companies [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	137	50
Registered Investment Companies [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	0	0
Other, Net [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	168	80
Other, Net [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	108	25
Other, Net [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	47	41
Other, Net [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	13	14
Below grade investments [Member] | Corporate Debt Instruments [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	380	391
Below grade investments [Member] | Corporate Debt Instruments [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	0	0
Below grade investments [Member] | Corporate Debt Instruments [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	380	391
Below grade investments [Member] | Corporate Debt Instruments [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	0	0
Above investment grade [Member] | Corporate Debt Instruments [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	1,372	714
Above investment grade [Member] | Corporate Debt Instruments [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	0	0
Above investment grade [Member] | Corporate Debt Instruments [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	1,371	714
Above investment grade [Member] | Corporate Debt Instruments [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments at fair value	$ 1	$ 0