Benefit Plans (Movements in Other Comprehensive Earnings (Losses)) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Amortization:
Net losses	$ 189	$ 281	$ 185
Prior service cost	5	10	10
Net transition obligation	0	0	1
Net losses - Post-employment	66	60	53
Prior service cost - Post-employment	0	0	0
Net transition obligation - Post-employment	0	0	0
Other income/expense:
Net losses	16	1	4
Prior service cost	5
Deferred income taxes	(42)	(49)	(37)
Amounts transferred to earnings as components of net periodic benefit cost	173	243	163
Net losses - Post-employment	0	0	0
Prior service cost - Post-employment	0
Deferred income taxes - Post-employment	(20)	(18)	(16)
Amounts transferred to earnings as components of net periodic benefit cost - Post-employment	46	42	37
Other movements during the year:
Net losses	(1,309)	1,157	(1,091)
Prior service cost	(5)	(1)	4
Net transition obligation	0	1
Deferred income taxes	167	(81)	144
Other movements during the year	(1,147)	1,076	(943)
Total movements in other comprehensive losses	(974)	1,319	(780)
Net losses - Post-employment	(126)	(109)	(129)
Prior service cost - Post-employment	0	0	0
Net transition obligation - Post-employment	0	0
Deferred income taxes - Post-employment	37	32	38
Other movements during the year - Post-employment	(89)	(77)	(91)
Total movements in other comprehensive earnings (losses) - Post-employment	(43)	(35)	(54)
Pension [Member]
Amortization:
Net losses	121	216	129
Prior service cost	6	10	10
Net transition obligation	0	0	1
Other income/expense:
Net losses	14	1	4
Prior service cost	5
Deferred income taxes	(21)	(29)	(20)
Amounts transferred to earnings as components of net periodic benefit cost	125	198	124
Other movements during the year:
Net losses	(1,149)	1,236	(931)
Prior service cost	(5)	(1)	0
Net transition obligation	0	1
Deferred income taxes	118	(103)	98
Other movements during the year	(1,036)	1,133	(833)
Total movements in other comprehensive losses	(911)	1,331	(709)
Postretirement [Member]
Amortization:
Net losses	2	5	3
Prior service cost	(1)	0	0
Net transition obligation	0	0	0
Other income/expense:
Net losses	2	0	0
Prior service cost	0
Deferred income taxes	(1)	(2)	(1)
Amounts transferred to earnings as components of net periodic benefit cost	2	3	2
Other movements during the year:
Net losses	(34)	30	(31)
Prior service cost	0	0	4
Net transition obligation	0	0
Deferred income taxes	12	(10)	8
Other movements during the year	(22)	20	(19)
Total movements in other comprehensive losses	$ (20)	$ 23	$ (17)