Income Taxes (Income Tax (Benefit) Provision) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
United States, current federal tax expense (benefit)	$ 203	$ (70)	$ 138
Current foreign tax expense (benefit)	432	182	213
Current state and local tax expense (benefit)	42	12	12
Current income tax expense (benefit)	677	124	363
United States, deferred federal income tax expense (benefit)	74	120	386
Deferred foreign income tax expense (benefit)	(406)	(119)	(233)
Deferred state and local income tax expense (benefit)	9	13	34
Deferred income tax expense (benefit)	(323)	14	187
Total income tax expense	$ 354	$ 138	$ 550