Income Taxes (Details 6) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2017
Tax Act Enactment [Line Items]
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	$ 31,000,000		$ 0
Foreign Earnings Repatriated	2.9
Total Operating and Capital Loss Carryforwards	$ 1,756,000,000
Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount			20,000,000
Effective Income Tax Rate Reconciliation Adjustments To Reserves And Prior Years	4.20%	2.80%			0.50%
Employee Service Share-based Compensation, Deferred Tax Benefit from Compensation Expense	$ 55,000,000		47,000,000			$ 117,000,000
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount	35,000,000
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	373,000,000		78,000,000
Tax Credit Carryforward, Valuation Allowance	200,000,000	$ 111,000,000	111,000,000	$ 111,000,000	$ 189,000,000	189,000,000	$ 189,000,000
Deferred Tax Assets, Gross	1,505,000,000	748,000,000	748,000,000	748,000,000
Deferred Tax Assets, Net	447,000,000	188,000,000	188,000,000	188,000,000
Deferred Tax Assets, Tax Deferred Expense	$ 718,000,000	$ 294,000,000	294,000,000	$ 294,000,000
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount			35,000,000			434,000,000
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	21.00%		21.00%	35.00%		21.00%
Limit on deductibility of interest expense							30.00%
Income tax provision	$ 79,000,000		297,000,000			934,000,000
Unrecognized Tax Benefits	188,000,000	$ 113,000,000	113,000,000	$ 113,000,000	$ 100,000,000	100,000,000	$ 100,000,000
Unrecognized Tax Benefits That Would Not Impact Effective Tax Rate	8,000,000	$ 10,000,000	10,000,000	$ 10,000,000
Deferred Tax Assets, Changes in Judgement [Member]
Tax Act Enactment [Line Items]
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	45,000,000
Deferred Tax Assets, Current Year Operations [Member]
Tax Act Enactment [Line Items]
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	9,000,000
Deferred Compensation, Share-based Payments [Member]
Tax Act Enactment [Line Items]
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount	31,000,000
Prior Year Divestiture [Member]
Tax Act Enactment [Line Items]
Effective Income Tax Rate Reconciliation Adjustments To Reserves And Prior Years		1900000000.00%
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount	34,000,000
Repatriation Tax Liability [Member]
Tax Act Enactment [Line Items]
Income tax provision			241,000,000
Remeasurement of Deferreds [Domain]
Tax Act Enactment [Line Items]
Income tax provision			47,000,000
Foreign [Member]
Tax Act Enactment [Line Items]
Total Operating and Capital Loss Carryforwards	408,000,000
State and Local Jurisdiction [Member]
Tax Act Enactment [Line Items]
Total Operating and Capital Loss Carryforwards	1,134,000,000
Tax Credit Carryforward, Valuation Allowance	100,000,000
Internal Revenue Service (IRS) [Member]
Tax Act Enactment [Line Items]
Total Operating and Capital Loss Carryforwards	214,000,000
Foreign Tax Credit [Domain]
Tax Act Enactment [Line Items]
Tax Credit Carryforward, Valuation Allowance	100,000,000
Tax Year 2018 [Member]
Tax Act Enactment [Line Items]
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount			156,000,000
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount			$ 399,000,000
Tax Year 2017 [Member]
Tax Act Enactment [Line Items]
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount						$ 34,000,000
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent							35.00%
Non-UK [Member]
Tax Act Enactment [Line Items]
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	7,000,000
Deferred Tax Assets, Gross	13,000,000
Deferred Tax Assets, Net	6,000,000
UNITED KINGDOM
Tax Act Enactment [Line Items]
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	366,000,000
Deferred Tax Assets, Gross	586,000,000
Deferred Tax Assets, Net	$ 220,000,000