Income Taxes (Unrecognized Tax Benefit Changes) (Details) $ in Millions	Mar. 31, 2019 USD ($)
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	$ 390
Italian Tax Authority Amnesty Program Potential Noncash Gain	90
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	750
Italian Tax Authority Amnesty Program Potential Noncash Gain	$ 110