Income Taxes (Current and Deferred Amounts of Provision) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current:
Federal	$ (82)	$ (256)	$ (20)
State and municipal	(12)	(22)	(21)
Foreign	(354)	(196)	(317)
Deferred:
Federal	64	(34)	(1,617)
State and municipal	13	4	(109)
Foreign	115	67	(70)
(Provision) benefit for income taxes	$ (256)	$ (437)	$ (2,154)