Income Taxes - Income Tax Provision (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current tax (provision) benefit:
Federal	$ 187	$ (4)	$ 0
State and local	(26)	5	(28)
International	(13)	(54)	(12)
Deferred tax provision:
Federal	(1,226)	(2,093)	(1,990)
State and local	(138)	(149)	(128)
Income tax provision	$ (1,216)	$ (2,295)	$ (2,158)