Income Taxes (Net Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Millions		Dec. 31, 2018	Dec. 31, 2017
Components of Deferred Tax Assets and Liabilities [Abstract]
Deferred tax assets		$ 8,835	$ 8,399
Deferred tax liabilities		(10,194)	(10,197)
Valuation allowance		(93)	(69)
Deferred Tax Liabilities, Net	[1]	$ 1,452	$ 1,867

[1] Included in the net deferred tax (liabilities)/assets as of December 31, 2018 and 2017 are deferred tax assets in the amounts of $4,275 and $4,636 related to Accumulated other comprehensive loss.