Benefit Plans (Movements in Other Comprehensive Earnings (Losses)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Amortization:
Net losses	$ 267	$ 189	$ 281
Prior service cost	4	5	10
Other income/expense:
Net losses	3	16	1
Prior service cost	1	5
Deferred income taxes	(48)	(42)	(49)
Amounts transferred to earnings as components of net periodic benefit cost	227	173	243
Other movements during the year:
Deferred income taxes	17	167	(81)
Net gains (losses) and prior service costs	(536)	(1,148)	1,079
Pension [Member]
Amortization:
Net losses	194	121	216
Prior service cost	4	6	10
Other income/expense:
Net losses	3	14	1
Prior service cost	1	5
Deferred income taxes	(26)	(21)	(29)
Amounts transferred to earnings as components of net periodic benefit cost	176	125	198
Postretirement [Member]
Amortization:
Net losses	4	2	5
Prior service cost	0	(1)	0
Other income/expense:
Net losses	0	2	0
Prior service cost	0	0
Deferred income taxes	(2)	(1)	(2)
Amounts transferred to earnings as components of net periodic benefit cost	2	2	3
Other movements during the year:
Net losses	12	(34)	30
Prior service cost		0	0
Net transition obligation			0
Deferred income taxes	(4)	12	(10)
Net gains (losses) and prior service costs	8	(22)	20
Total movements in other comprehensive earnings (losses)	10	(20)	23
Postemployment Benefit Plans [Member]
Amortization:
Net losses	69	66	60
Prior service cost	0	0	0
Other income/expense:
Net losses	0	0	0
Prior service cost	0	0
Deferred income taxes	(20)	(20)	(18)
Amounts transferred to earnings as components of net periodic benefit cost	49	46	42
Other movements during the year:
Net losses	(58)	(126)	(109)
Prior service cost		0	0
Net transition obligation			0
Deferred income taxes	17	37	32
Net gains (losses) and prior service costs	(41)	(89)	(77)
Total movements in other comprehensive earnings (losses)	8	(43)	(35)
AOCI Attributable to Noncontrolling Interest [Member]
Other movements during the year:
Net losses	(556)	(1,309)	1,157
Prior service cost		(5)	(1)
Net transition obligation			1
Deferred income taxes	17	167	(81)
Net gains (losses) and prior service costs	(539)	(1,147)	1,076
Total movements in other comprehensive earnings (losses)	(312)	(974)	1,319
AOCI Attributable to Noncontrolling Interest [Member] | Pension [Member]
Other movements during the year:
Net losses	(510)	(1,149)	1,236
Prior service cost		(5)	(1)
Net transition obligation			1
Deferred income taxes	4	118	(103)
Net gains (losses) and prior service costs	(506)	(1,036)	1,133
Total movements in other comprehensive earnings (losses)	$ (330)	$ (911)	$ 1,331