Financial Statement Presentation Adoption of ASU 842 2019 (Details) - USD ($) $ in Millions	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other Assets, Noncurrent	$ 1,771	$ 1,767	$ 1,514
Accrued Liabilities, Current	914	989	962
Other Liabilities, Noncurrent	$ 2,828	$ 2,949	2,723
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other Assets, Noncurrent			253
Accrued Liabilities, Current			27
Other Liabilities, Noncurrent			$ 226