Income Taxes - Tax Contingencies (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Income Tax Contingency [Line Items]
Liabilities associated with uncertain tax positions	$ 194	$ 188
Unrecognized tax benefits, income tax penalties and interest accrued	16	14
Noncurrent Deferred Tax Assets
Income Tax Contingency [Line Items]
Liabilities associated with uncertain tax positions	2	1
Other Taxes Payable
Income Tax Contingency [Line Items]
Liabilities associated with uncertain tax positions	$ 192	$ 187