Income Taxes (Income Tax Payables and Income Tax Receivables) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income taxes receivable—current	$ 138	$ 131
Income Taxes Receivable, Noncurrent	9	10
Total income taxes receivable	147	141
Income taxes payable—current	284	172
Income taxes payable—noncurrent	0	0
Total income taxes payable	$ 284	$ 172