Pension and Postretirement Benefit Plans (Components of net periodic benefit cost and other information) (Details 6) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
United States Qualified and Non-qualified Pension Benefits
Summary of changes in fair values of assets
Fair value, beginning balance	$ 13,895
Foreign currency exchange	0	0
Fair value, ending balance	14,818	13,895
United States Qualified and Non-qualified Pension Benefits | Level 3
Summary of changes in fair values of assets
Fair value, beginning balance	3,484	3,531
Net transfers into / (out of) level 3	100	(101)
Purchases, sales, issuances, and settlements, net	(99)	(238)
Realized gain (loss)	187	181
Change in unrealized gains/(losses) relating to instruments sold during the period	54	(42)
Change in unrealized gains/(losses) relating to instruments still held at the reporting date	151	153
Fair value, ending balance	3,877	3,484
United States Qualified and Non-qualified Pension Benefits | Equities
Summary of changes in fair values of assets
Fair value, ending balance	3,587	3,538
United States Qualified and Non-qualified Pension Benefits | Equities | Level 3
Summary of changes in fair values of assets
Fair value, beginning balance	397	421
Net transfers into / (out of) level 3	0	0
Purchases, sales, issuances, and settlements, net	(43)	(92)
Realized gain (loss)	2	10
Change in unrealized gains/(losses) relating to instruments sold during the period	(12)	(5)
Change in unrealized gains/(losses) relating to instruments still held at the reporting date	40	63
Fair value, ending balance	384	397
United States Qualified and Non-qualified Pension Benefits | Fixed income
Summary of changes in fair values of assets
Fair value, ending balance	5,652	4,670
United States Qualified and Non-qualified Pension Benefits | Fixed income | Level 3
Summary of changes in fair values of assets
Fair value, beginning balance	2	2
Net transfers into / (out of) level 3	0	0
Purchases, sales, issuances, and settlements, net	(1)	0
Realized gain (loss)	0	0
Change in unrealized gains/(losses) relating to instruments sold during the period	0	0
Change in unrealized gains/(losses) relating to instruments still held at the reporting date	(1)	0
Fair value, ending balance	0	2
United States Qualified and Non-qualified Pension Benefits | Private equity
Summary of changes in fair values of assets
Fair value, ending balance	2,502	2,448
United States Qualified and Non-qualified Pension Benefits | Private equity | Level 3
Summary of changes in fair values of assets
Fair value, beginning balance	2,427	2,136
Net transfers into / (out of) level 3	0	0
Purchases, sales, issuances, and settlements, net	(260)	54
Realized gain (loss)	185	126
Change in unrealized gains/(losses) relating to instruments sold during the period	64	3
Change in unrealized gains/(losses) relating to instruments still held at the reporting date	71	108
Fair value, ending balance	2,487	2,427
United States Qualified and Non-qualified Pension Benefits | Absolute return
Summary of changes in fair values of assets
Fair value, ending balance	2,173	1,833
United States Qualified and Non-qualified Pension Benefits | Absolute return | Level 3
Summary of changes in fair values of assets
Fair value, beginning balance	658	865
Net transfers into / (out of) level 3	100	(101)
Purchases, sales, issuances, and settlements, net	205	(104)
Realized gain (loss)	0	46
Change in unrealized gains/(losses) relating to instruments sold during the period	2	(30)
Change in unrealized gains/(losses) relating to instruments still held at the reporting date	41	(18)
Fair value, ending balance	1,006	658
United States Qualified and Non-qualified Pension Benefits | Commodities
Summary of changes in fair values of assets
Fair value, ending balance	0	88
United States Qualified and Non-qualified Pension Benefits | Commodities | Level 3
Summary of changes in fair values of assets
Fair value, beginning balance	0	107
Net transfers into / (out of) level 3	0	0
Purchases, sales, issuances, and settlements, net	0	(96)
Realized gain (loss)	0	(1)
Change in unrealized gains/(losses) relating to instruments sold during the period	0	(10)
Change in unrealized gains/(losses) relating to instruments still held at the reporting date	0	0
Fair value, ending balance	0	0
International Qualified and Non-qualified Pension Benefits
Summary of changes in fair values of assets
Fair value, beginning balance	5,757
Foreign currency exchange	(554)	(94)
Fair value, ending balance	5,998	5,757
International Qualified and Non-qualified Pension Benefits | Level 3
Summary of changes in fair values of assets
Fair value, beginning balance	667	597
Net transfers into / (out of) level 3	(32)	0
Foreign currency exchange	(75)	6
Purchases, sales, issuances, and settlements, net	12	49
Realized gain (loss)	2	2
Change in unrealized gains/(losses) relating to instruments sold during the period	(2)	1
Change in unrealized gains/(losses) relating to instruments still held at the reporting date	30	12
Fair value, ending balance	602	667
International Qualified and Non-qualified Pension Benefits | Equities
Summary of changes in fair values of assets
Fair value, ending balance	2,131	2,282
International Qualified and Non-qualified Pension Benefits | Equities | Level 3
Summary of changes in fair values of assets
Fair value, beginning balance	5	5
Net transfers into / (out of) level 3	0	0
Foreign currency exchange	(1)	0
Purchases, sales, issuances, and settlements, net	0	0
Realized gain (loss)	0	0
Change in unrealized gains/(losses) relating to instruments sold during the period	0	0
Change in unrealized gains/(losses) relating to instruments still held at the reporting date	0	0
Fair value, ending balance	4	5
International Qualified and Non-qualified Pension Benefits | Fixed income
Summary of changes in fair values of assets
Fair value, ending balance	2,915	2,565
International Qualified and Non-qualified Pension Benefits | Fixed income | Level 3
Summary of changes in fair values of assets
Fair value, beginning balance	37	36
Net transfers into / (out of) level 3	0	0
Foreign currency exchange	(4)	(2)
Purchases, sales, issuances, and settlements, net	(14)	(2)
Realized gain (loss)	0	0
Change in unrealized gains/(losses) relating to instruments sold during the period	(1)	0
Change in unrealized gains/(losses) relating to instruments still held at the reporting date	1	5
Fair value, ending balance	19	37
International Qualified and Non-qualified Pension Benefits | Private equity
Summary of changes in fair values of assets
Fair value, ending balance	154	165
International Qualified and Non-qualified Pension Benefits | Private equity | Level 3
Summary of changes in fair values of assets
Fair value, beginning balance	75	71
Net transfers into / (out of) level 3	0	0
Foreign currency exchange	(6)	(1)
Purchases, sales, issuances, and settlements, net	(2)	1
Realized gain (loss)	2	2
Change in unrealized gains/(losses) relating to instruments sold during the period	(1)	0
Change in unrealized gains/(losses) relating to instruments still held at the reporting date	10	2
Fair value, ending balance	78	75
International Qualified and Non-qualified Pension Benefits | Absolute return
Summary of changes in fair values of assets
Fair value, ending balance	605	619
International Qualified and Non-qualified Pension Benefits | Absolute return | Level 3
Summary of changes in fair values of assets
Fair value, beginning balance	550	485
Net transfers into / (out of) level 3	(32)	0
Foreign currency exchange	(64)	9
Purchases, sales, issuances, and settlements, net	28	50
Realized gain (loss)	0	0
Change in unrealized gains/(losses) relating to instruments sold during the period	0	1
Change in unrealized gains/(losses) relating to instruments still held at the reporting date	19	5
Fair value, ending balance	501	550
Postretirement Benefits
Summary of changes in fair values of assets
Fair value, beginning balance	1,394
Foreign currency exchange	0	0
Fair value, ending balance	1,428	1,394
Postretirement Benefits | Level 3
Summary of changes in fair values of assets
Fair value, beginning balance	203	218
Net transfers into / (out of) level 3	(2)	0
Purchases, sales, issuances, and settlements, net	(39)	(38)
Realized gain (loss)	29	12
Change in unrealized gains/(losses) relating to instruments sold during the period	(5)	(4)
Change in unrealized gains/(losses) relating to instruments still held at the reporting date	24	15
Fair value, ending balance	210	203
Postretirement Benefits | Equities
Summary of changes in fair values of assets
Fair value, ending balance	676	670
Postretirement Benefits | Equities | Level 3
Summary of changes in fair values of assets
Fair value, beginning balance	16	16
Net transfers into / (out of) level 3	(2)	0
Purchases, sales, issuances, and settlements, net	(2)	(3)
Realized gain (loss)	0	0
Change in unrealized gains/(losses) relating to instruments sold during the period	0	0
Change in unrealized gains/(losses) relating to instruments still held at the reporting date	2	3
Fair value, ending balance	14	16
Postretirement Benefits | Fixed income
Summary of changes in fair values of assets
Fair value, ending balance	457	427
Postretirement Benefits | Fixed income | Level 3
Summary of changes in fair values of assets
Fair value, beginning balance	0	0
Net transfers into / (out of) level 3	0	0
Purchases, sales, issuances, and settlements, net	0	0
Realized gain (loss)	0	0
Change in unrealized gains/(losses) relating to instruments sold during the period	0	0
Change in unrealized gains/(losses) relating to instruments still held at the reporting date	0	0
Fair value, ending balance	0	0
Postretirement Benefits | Private equity
Summary of changes in fair values of assets
Fair value, ending balance	160	162
Postretirement Benefits | Private equity | Level 3
Summary of changes in fair values of assets
Fair value, beginning balance	161	170
Net transfers into / (out of) level 3	0	0
Purchases, sales, issuances, and settlements, net	(45)	(27)
Realized gain (loss)	29	10
Change in unrealized gains/(losses) relating to instruments sold during the period	(5)	(3)
Change in unrealized gains/(losses) relating to instruments still held at the reporting date	19	11
Fair value, ending balance	159	161
Postretirement Benefits | Absolute return
Summary of changes in fair values of assets
Fair value, ending balance	79	63
Postretirement Benefits | Absolute return | Level 3
Summary of changes in fair values of assets
Fair value, beginning balance	26	28
Net transfers into / (out of) level 3	0	0
Purchases, sales, issuances, and settlements, net	8	(4)
Realized gain (loss)	0	2
Change in unrealized gains/(losses) relating to instruments sold during the period	0	(1)
Change in unrealized gains/(losses) relating to instruments still held at the reporting date	3	1
Fair value, ending balance	37	26
Postretirement Benefits | Commodities
Summary of changes in fair values of assets
Fair value, ending balance	0	3
Postretirement Benefits | Commodities | Level 3
Summary of changes in fair values of assets
Fair value, beginning balance	0	4
Net transfers into / (out of) level 3	0	0
Purchases, sales, issuances, and settlements, net	0	(4)
Realized gain (loss)	0	0
Change in unrealized gains/(losses) relating to instruments sold during the period	0	0
Change in unrealized gains/(losses) relating to instruments still held at the reporting date	0	0
Fair value, ending balance	$ 0	$ 0