Accounting Policies - Narrative (Details) - USD ($) $ in Millions	Mar. 31, 2020	Jan. 01, 2020	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings	$ 5,444		$ 6,113
Accounts receivable	2,025		1,941
Deferred income taxes	$ 1,261		$ 1,527
Accounting Standards Update 2016-13 \| Restatement Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings		$ (12)
Accounts receivable		(15)
Deferred income taxes		$ 3

Amount, after allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as current.

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