Income Taxes - Tax Credit Carryforwards (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended			6 Months Ended	12 Months Ended
	Oct. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Jun. 30, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Tax Credit Carryforward [Line Items]
Deferred tax assets not subject to expiration						$ 12
Tax benefit due to step-up in amortizable tax basis				$ (695)		$ (199)	$ 9	$ 695
Foreign exchange remeasurement of deferred tax asset					$ 376
Federal statutory rate						21.00%	21.00%	35.00%
TCJA income tax benefit			$ (3,100)
Provisional amounts recorded as component of income tax expense		$ 463
Foreign earnings repatriated			1,400
Foreign Earnings Repatriated Adjustment, Amount						$ 18
Tax reconciliation, reduction to provisional income taxes						213
Deferred tax liabilities on undistributed foreign earnings		2,930				2,610	$ 2,930
Deferred tax liabilities not recognized on undistributed foreign earnings			$ 1,700					$ 1,700
Provisional tax expense		(445)				415	190	$ 3,288
State Tax Credit Carryforward
Tax Credit Carryforward [Line Items]
Tax credit carryforward						140
Tax Period 2020
Tax Credit Carryforward [Line Items]
Deferred tax assets subject to expiration						246
Tax Period 2024
Tax Credit Carryforward [Line Items]
Deferred tax assets subject to expiration						104
Swiss Tax authorities
Tax Credit Carryforward [Line Items]
Provisional tax expense	$ (389)
Federal
Tax Credit Carryforward [Line Items]
Operating loss carryforwards						11
State
Tax Credit Carryforward [Line Items]
Operating loss carryforwards						55
Foreign
Tax Credit Carryforward [Line Items]
Operating loss carryforwards						361
Other Liabilities
Tax Credit Carryforward [Line Items]
Deferred tax liabilities on undistributed foreign earnings		$ 968				$ 884	$ 968