Employee Benefit Plans (Obligations and Funded Status) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Pension Benefits U.S. Plans [Member]
Change in benefit obligations:
Benefit obligations at January 1,	$ 8,130	$ 8,937
Service costs	183	214
Interest costs	413	367
Plan participants’ contributions	0	0
Net actuarial (gains) losses	1,461	(967)
Settlements and curtailments	(13)	0
Change in benefits and other	574	26
Benefits paid	(486)	(447)
Effect of foreign currency translation	0	0
Benefit obligations at December 31,	10,262	8,130
Change in plan assets
Fair value of plan assets at January 1,	7,305	7,390
Actual return on plan assets	1,018	(20)
Change in benefits and other	523	28
Plan participants’ contributions	0	0
Employer contributions	390	354
Benefits paid	(486)	(447)
Fair value of plan assets at December 31,	8,750	7,305
Over (under) funded status at December 31,	(1,512)	(825)
Amounts recognized in the consolidated balance sheets
Other assets	0	213
Other liabilities	(1,512)	(1,038)
Net amount recognized	(1,512)	(825)
Accumulated other comprehensive (income) loss:
Net actuarial (gains) losses	3,034	2,207
Prior service costs (credit)	(2)	17
Accumulated other comprehensive (income) loss, before income tax	3,032	2,224
Accumulated benefit obligation	9,729	7,689
Other Postretirement Benefits U.S. Plans [Member]
Change in benefit obligations:
Benefit obligations at January 1,	1,861	2,402
Service costs	14	20
Interest costs	92	92
Plan participants’ contributions	30	30
Net actuarial (gains) losses	264	(550)
Settlements and curtailments	(6)	0
Change in benefits and other	(16)	0
Benefits paid	(109)	(133)
Effect of foreign currency translation	(1)	0
Benefit obligations at December 31,	2,129	1,861
Change in plan assets
Fair value of plan assets at January 1,	1,352	1,320
Actual return on plan assets	112	57
Change in benefits and other	0	0
Plan participants’ contributions	30	30
Employer contributions	41	78
Benefits paid	(109)	(133)
Fair value of plan assets at December 31,	1,426	1,352
Over (under) funded status at December 31,	(703)	(509)
Amounts recognized in the consolidated balance sheets
Other assets	0	0
Other liabilities	(703)	(509)
Net amount recognized	(703)	(509)
Accumulated other comprehensive (income) loss:
Net actuarial (gains) losses	420	209
Prior service costs (credit)	(10)	1
Accumulated other comprehensive (income) loss, before income tax	$ 410	$ 210