Income Taxes - Allocation of Income Tax Benefit/(Provision) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income tax benefit applicable to:
Income from operations	$ 141	$ 121	$ 1,995
Other comprehensive income/(loss)	$ 12	$ 3	$ 0