Employee Benefit Plans, Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Employee Benefit Plans (Textual)
The percentage of the higher of the projected benefit obligation or market-related value of plan assets in excess of which net actuarial losses are amortized	10.00%
Pension Plans [Member]
Components of net periodic benefit cost:
Service cost	$ 111	$ 109	$ 120
Interest cost	84	98	91
Expected return on plan assets	(139)	(133)	(133)
Amortization of:
Net actuarial (gain) loss	49	62	35
Prior service cost (credit)	(20)	(22)	(22)
Special charges (credits)	(7)	7	3
Net periodic benefit cost	78	121	94
Other Postretirement Benefit Plans [Member]
Components of net periodic benefit cost:
Service cost	7	8	7
Interest cost	12	14	15
Expected return on plan assets	0	0	0
Amortization of:
Net actuarial (gain) loss	(1)	0	(1)
Prior service cost (credit)	(16)	(18)	(18)
Special charges (credits)	0	0	0
Net periodic benefit cost	$ 2	$ 4	$ 3