Income Taxes (Narrative) (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Taxes [Line Items]
Provisional expense	$ 1,600
Accumulated foreign earning provisional tax charge	1,400			$ 1,400
Transition tax				2,200
Reversal of previously recorded deferred tax liabilities				700
Other items				100
Re-measurement provisional charge	200			200
Income tax provision charge			$ 31
Current income tax charge from transition tax on foreign earnings			185
TCJA, income tax payable	1,700			1,700
TCJA. income tax payable included in income taxes and other liabilities	$ 1,600			1,600
Foreign tax credits related to foreign withholding taxes				500
Income tax payable			100
Income tax payable noncurrent		$ 1,200	1,500
Unrecognized tax benefits that, if recognized, would impact effective tax rate		50
Income tax penalties and interest income (expense) recognized		$ (4)	$ 4	$ (11)
Percentage increase (decrease) in effective income tax rate		0.30%	(17.80%)	12.80%
Net operating loss carryforwards		$ 486	$ 452
Net operating loss carryforwards with unlimited period		98	87
Valuation allowances		304	257
Adjustment Of 2017 Provisional Estimates [Member]
Income Taxes [Line Items]
Deferred income tax benefit due to recognition of net operating losses in New York state			$ 154
Tax Years 2015-2018 [Member]
Income Taxes [Line Items]
Tax adjustments		$ (67)
Minimum [Member]
Income Taxes [Line Items]
Foreign and U.S. state jurisdictions have statutes of limitations		3 years
Maximum [Member]
Income Taxes [Line Items]
Foreign and U.S. state jurisdictions have statutes of limitations		5 years
RBH [Member]
Income Taxes [Line Items]
Tax adjustments		$ (49)
United States [Member]
Income Taxes [Line Items]
Open tax years		2015 and onward