Income Taxes (Unrecognized Tax Benefit Changes) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2021	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Significant Change In Unrecognized Tax Benefits Is Reasonably Possible [Line Items]
Effective Income Tax Rate Reconciliation, Percent	23.90%	1.00%		26.50%	(22.00%)
Effective Income Tax Rate Reconciliation, Change in U.K. Enacted Tax Rate, Amount	$ 73
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Impairment Losses, Amount		$ 3,200			$ 3,200
Effective Income Tax Rate Reconciliation, Debt Exchange, Amount		60			60
Effective Income Tax Rate Reconciliation, Tax Credit, Foreign, Amount		46			46
Effective Income Tax Rate Reconciliation, Deferred Tax Assets, Amount					415
Unrecognized Tax Benefits, Interest on Income Taxes Expense	10	$ 11		$ 19	$ 22
Unrecognized Tax Benefits, Interest on Income Taxes Accrued	154			154		$ 141
Forcepoint
Significant Change In Unrecognized Tax Benefits Is Reasonably Possible [Line Items]
Effective Income Tax Rate Reconciliation, Disposition of Business, Amount				148
Minimum [Member]
Significant Change In Unrecognized Tax Benefits Is Reasonably Possible [Line Items]
Decrease in Unrecognized Tax Benefits is Reasonably Possible, Estimated Range of Change	35			35
Minimum [Member] | Forecast [Member]
Significant Change In Unrecognized Tax Benefits Is Reasonably Possible [Line Items]
Effective Income Tax Rate Reconciliation, Tax Settlement, Amount			$ 20
Maximum [Member]
Significant Change In Unrecognized Tax Benefits Is Reasonably Possible [Line Items]
Decrease in Unrecognized Tax Benefits is Reasonably Possible, Estimated Range of Change	$ 410			$ 410
Maximum [Member] | Forecast [Member]
Significant Change In Unrecognized Tax Benefits Is Reasonably Possible [Line Items]
Effective Income Tax Rate Reconciliation, Tax Settlement, Amount			$ 100