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Equity - Narrative (Details) - USD ($) $ in Millions		1 Months Ended	7 Months Ended	12 Months Ended
	Oct. 29, 2018	Apr. 30, 2019	Apr. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Oct. 25, 2018
Equity [Abstract]
Common stock, shares authorized				6,500,000,000	6,500,000,000
Preferred stock, shares authorized				20,000,000
Accelerated Share Repurchases [Line Items]
Treasury stock acquired				$ 4,780	$ 9,091	$ 4,014
Accelerated Share Repurchase Agreement, October 29, 2018
Accelerated Share Repurchases [Line Items]
Purchases of treasury stock (in shares)	56,700,000
Accelerated Share Repurchase Agreement
Accelerated Share Repurchases [Line Items]
Shares authorized to be repurchased (in shares)							$ 5,000
Purchases of treasury stock (in shares)		7,700,000	64,400,000
Payment under ASR agreement	$ 5,000
Treasury stock acquired	4,000
Decrease in other-paid-in capital	$ 1,000

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Amount of cash receipt from (payment to) bank; or stock received from (issuance to) bank in the settlement of the accelerated share repurchase agreement.

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The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.

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