Income Taxes US Tax Reform (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)
US Tax Reform [Line Items]
Undistributed earnings of foreign subsidiaries	$ 2,500
US Tax Reform, Provisional Tax Expense	130
Impact from remeasurement of net US deferred income taxes [Member]
US Tax Reform [Line Items]
US Tax Reform, Provisional Tax Expense	94
Impact from repatriation tax on undistributed foreign earnings [Member]
US Tax Reform [Line Items]
US Tax Reform, Provisional Tax Expense	$ 36