Employee Benefit Plans (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Total revenue from annuity and life insurance contracts recognized		$ 56	$ 58	$ 55
Total investment income (loss) from annuity and life insurance contracts		1,100	660	(125)
Defined Contribution Plan, Cost		72	81	80
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Aggregate projected benefit obligations		11,409	$ 10,741	$ 10,293
Estimated net actuarial losses amortized into net periodic benefit cost over the next year		171
Estimated prior service cost amortized into net periodic benefit cost over the next year		$ (1)
Weighted average expected return on plan assets		6.00%	6.00%	6.25%
Pension Benefits | U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Aggregate projected benefit obligations		$ 10,500	$ 9,859
Pension Benefits | Non- U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Aggregate projected benefit obligations		909	882
Pension Benefits | Scenario, Forecast | U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Weighted average expected return on plan assets	5.75%
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Aggregate projected benefit obligations		1,674	$ 1,759	$ 1,892
Estimated net actuarial losses amortized into net periodic benefit cost over the next year		(6)
Estimated prior service cost amortized into net periodic benefit cost over the next year		$ (19)
Weighted average expected return on plan assets		5.36%	5.53%	5.70%
Other Postretirement Benefits | U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Aggregate projected benefit obligations		$ 1,648	$ 1,734
Expected future discretionary contributions		50
Other Postretirement Benefits | Non- U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Aggregate projected benefit obligations		26	25
Other Postretirement Benefits | Scenario, Forecast | U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Weighted average expected return on plan assets	5.11%
United States Pension Plan of US Entity, Qualified [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected future discretionary contributions		150
United States Pension Plan of US Entity, Non Qualified [Member]
Defined Benefit Plan Disclosure [Line Items]
Aggregate projected benefit obligations		1,200	$ 1,100
Expected future discretionary contributions		$ 70