Employee Benefit Plans (Retirement Plan Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Settlement charges	$ 117
Defined contribution plans	50	$ 57	$ 57
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost (benefits earned during the period)	66	78	82
Interest cost	93	106	113
Expected return on plan assets	(146)	(145)	(137)
Settlement charges	117	0	(5)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment	(1)	0	0
Amortization of actuarial loss	55	65	56
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	(19)	(7)	2
Net periodic defined benefit plan expense	165	97	111
Pension Expense	215	154	168
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost (benefits earned during the period)	2	2	3
Interest cost	5	6	8
Settlement charges	0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment	0	0	(38)
Amortization of actuarial loss	3	4	3
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	(15)	(13)	(17)
Net periodic defined benefit plan expense	(5)	(1)	(41)
Pension Expense	$ (5)	$ (1)	$ (41)