Income Tax (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	$ 32
Proceeds from Income Tax Refunds	59	$ 22	$ 2
Cash paid for income taxes	167	66	144
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	155
Decrease in Unrecognized Tax Benefits is Reasonably Possible	312
Cash paid for income taxes	167	66	144
Tax Adjustments, Settlements, and Unusual Provisions	0	0	(62)
Deferred Tax Assets, Valuation Allowance	251	236
Proceeds from Income Tax Refunds	59	22	2
Deferred Tax Liability Not Recognized, Amount of Unrecognized Deferred Tax Liability	2,700	1,600
Subsidiary Net Operating Loss	20	44
Operating Loss Carryforwards	900
Unrecognized Tax Benefits	342	333	325	$ 321
Unrecognized Tax Benefits, Interest on Income Taxes Expense	11	12	$ (3)
Unrecognized Tax Benefits, Interest on Income Taxes Accrued	$ 34	$ 23