Income and Other Taxes - Income Tax Expense (Benefit), Current Deferred, by Jurisdiction (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Current Federal Tax Expense (Benefit)	$ 3	$ (3)	$ 37
Deferred Federal Income Tax Expense (Benefit)	58	98	83
Current Foreign Tax Expense	19	43	46
Deferred Foreign Income Tax Expense (Benefit)	(34)	5	57
Current State Tax Expense	8	15	29
Deferred State Income Tax (Benefit) Expense	10	21	(5)
Income Tax Expense	$ 64	$ 179	$ 247