Income Taxes - Deferred income taxes (assets and liabilities netted by jurisdiction) as classified in the Consolidated Statements of Financial Position (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Deferred income taxes
Deferred tax assets — non-current	$ 561	$ 389
Deferred tax liabilities — non-current	(181)	(127)
Net deferred tax asset	$ 380	$ 262