Taxation (Reconciliation of Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits, beginning of year	$ 47	$ 14
Additions based on tax provisions related to the current year	5	12
Additions based on tax positions related to prior years	24	23
Reductions for the lapse of the applicable statutes of limitations	0	(2)
Unrecognized Tax Benefits, end of year	$ 76	$ 47