Goodwill (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Goodwill [Line Items]
Goodwill	$ 1,242	$ 1,607	$ 1,242	$ 1,607	$ 1,607
Accumulated impairment loss	1,035		1,035		670
Goodwill impairment charge	$ 365	$ 0	$ 365	$ 0
RBWM [Member]
Goodwill [Line Items]
Goodwill					$ 737

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of accumulated impairment loss for an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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