Income Taxes Income Tax Examination (Details) $ in Millions	3 Months Ended
	Jun. 30, 2019 USD ($)
Closure of IRS audits of 2014-2016 and Italian Tax Authority amnesty program [Domain]
Income Tax Examination [Line Items]
Tax Settlement Gain (Loss) Noncash	$ 307
Interest Income [Member] | Closure of IRS audits of 2014-2016 and Italian Tax Authority amnesty program [Domain]
Income Tax Examination [Line Items]
Tax Settlement Gain (Loss) Noncash	56
Minimum [Member]
Income Tax Examination [Line Items]
Tax Settlement Potential Gain (Loss) Noncash	25
Maximum [Member]
Income Tax Examination [Line Items]
Tax Settlement Potential Gain (Loss) Noncash	$ 70