Interim Consolidated Financial Statements (Details) - USD ($) $ in Millions	Mar. 31, 2020	Jan. 01, 2020	Mar. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of changes in accounting principle	$ 1		$ 2
Trade Accounts Receivable
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of changes in accounting principle		$ (1)
Retained Earnings [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of changes in accounting principle	$ 1	$ 1	$ 2