Benefit Plans (Amounts Recorded in Accumulated Other Comprehensive Losses) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Accumulated other comprehensive losses	$ (1,378)	$ (2,040)	$ (1,887)	$ (1,484)
Accumulated Defined Benefit Plans Adjustment [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Accumulated other comprehensive losses	(1,273)	(2,414)	(2,062)	(1,811)
Accumulated Defined Benefit Plans Adjustment, Net Unamortized Gain (Loss) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net loss	(2,358)	(4,272)
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Cost (Credit) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net loss	274	318
Accumulated Defined Benefit Plans Adjustment, Net Deferred Tax Impact [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Deferred income taxes	811	1,540
Pension [Member] | Accumulated Defined Benefit Plans Adjustment [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Accumulated other comprehensive losses	(1,051)	(1,968)
Pension [Member] | Accumulated Defined Benefit Plans Adjustment, Net Unamortized Gain (Loss) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net loss	(1,691)	(3,186)
Pension [Member] | Accumulated Defined Benefit Plans Adjustment, Net Prior Service Cost (Credit) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net loss	(33)	(36)
Pension [Member] | Accumulated Defined Benefit Plans Adjustment, Net Deferred Tax Impact [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Deferred income taxes	673	1,254
Postretirement Benefit Plan [Member] | Accumulated Defined Benefit Plans Adjustment [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Accumulated other comprehensive losses	(142)	(342)
Postretirement Benefit Plan [Member] | Accumulated Defined Benefit Plans Adjustment, Net Unamortized Gain (Loss) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net loss	(539)	(917)
Postretirement Benefit Plan [Member] | Accumulated Defined Benefit Plans Adjustment, Net Prior Service Cost (Credit) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net loss	307	354
Postretirement Benefit Plan [Member] | Accumulated Defined Benefit Plans Adjustment, Net Deferred Tax Impact [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Deferred income taxes	90	221
Postemployment Benefit Plans [Member] | Accumulated Defined Benefit Plans Adjustment [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Accumulated other comprehensive losses	(80)	(104)
Postemployment Benefit Plans [Member] | Accumulated Defined Benefit Plans Adjustment, Net Unamortized Gain (Loss) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net loss	(128)	(169)
Postemployment Benefit Plans [Member] | Accumulated Defined Benefit Plans Adjustment, Net Prior Service Cost (Credit) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net loss	0	0
Postemployment Benefit Plans [Member] | Accumulated Defined Benefit Plans Adjustment, Net Deferred Tax Impact [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Deferred income taxes	$ 48	$ 65