Equity - Narrative (Details) - USD ($) shares in Millions		1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Oct. 29, 2018	Apr. 30, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Oct. 25, 2018
Accelerated Share Repurchases [Line Items]
Treasury stock shares acquired			$ 1,405,000,000	$ 996,000,000	$ 3,730,000,000	$ 3,158,000,000
Accelerated Share Repurchase Agreement
Accelerated Share Repurchases [Line Items]
Share repurchase program authorized amount								$ 5,000,000,000
Treasury stock shares purchased (in shares)	56.7	7.7					64.4
Payment under ASR agreement	$ 5,000,000,000
Treasury stock shares acquired	4,000,000,000
Decrease in other-paid-in capital	$ 1,000,000,000