Employee Benefit Plans (Retirement Plan Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plans	$ 57	$ 52	$ 50
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost (benefits earned during the period)	82	92	71
Interest cost	113	112	126
Expected return on plan assets	(137)	(129)	(155)
Settlement charges	(5)	60	95
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments	0	0	0
Amortization of actuarial loss	56	69	36
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	2	2	3
Net periodic defined benefit plan expense	111	206	176
Pension Expense	168	258	226
Other Postretirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost (benefits earned during the period)	3	5	4
Interest cost	8	8	8
Settlement charges	0
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments	(38)	0	0
Amortization of actuarial loss	3	7	2
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	(17)	(17)	(18)
Net periodic defined benefit plan expense	(41)	3	(4)
Pension Expense	$ (41)	$ 3	$ (4)