CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (UNAUDITED) - USD ($) shares in Millions, $ in Millions		Total	Preferred Stock		Common Stock and Additional Paid-in Capital	Right to Recover for Covered Losses	Accumulated Income	Accumulated Other Comprehensive Income (Loss)
Beginning balance (in shares) at Sep. 30, 2022			5
Balance as of beginning of period at Sep. 30, 2022		$ 35,581	$ 2,324	[1]	$ 19,545	$ (35)	$ 16,116	$ (2,369)
Beginning balance (in shares) at Sep. 30, 2022					1,890
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		8,436					8,436
Other comprehensive income (loss)		1,379						1,379
VE territory covered losses incurred		(15)				(15)
Recovery through conversion rate adjustment		1	$ (14)			15
Conversion to class A common stock (in shares)			0	[2]	7
Conversion to class A common stock		0	$ (425)		$ 425
Share-based compensation		400			$ 400
Stock issued under equity plans (in shares)					3
Stock issued under equity plans		118			$ 118
Restricted stock and performance-based shares settled in cash for taxes (in shares)	[2]				0
Restricted stock and performance-based shares settled in cash for taxes		(118)			$ (118)
Cash dividends declared and paid, at a quarterly amount per class A common stock		(1,886)					(1,886)
Repurchase of class A common stock (in shares)					(26)
Repurchase of class A common stock		(5,331)			$ (275)		(5,056)
Ending balance (in shares) at Mar. 31, 2023			5
Balance as of end of period at Mar. 31, 2023		38,565	$ 1,885	[1]	$ 20,095	(35)	17,610	(990)
Ending balance (in shares) at Mar. 31, 2023					1,874
Beginning balance (in shares) at Dec. 31, 2022			5
Balance as of beginning of period at Dec. 31, 2022		36,924	$ 1,981		$ 19,827	(28)	16,403	(1,259)
Beginning balance (in shares) at Dec. 31, 2022					1,881
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		4,257					4,257
Other comprehensive income (loss)		269						269
VE territory covered losses incurred		(7)				(7)
Conversion to class A common stock (in shares)			0	[3]	2
Conversion to class A common stock		0	$ (96)		$ 96
Share-based compensation		223			$ 223
Stock issued under equity plans (in shares)					1
Stock issued under equity plans		62			$ 62
Restricted stock and performance-based shares settled in cash for taxes (in shares)	[3]				0
Restricted stock and performance-based shares settled in cash for taxes		(6)			$ (6)
Cash dividends declared and paid, at a quarterly amount per class A common stock		(941)					(941)
Repurchase of class A common stock (in shares)					(10)
Repurchase of class A common stock		(2,216)			$ (107)		(2,109)
Ending balance (in shares) at Mar. 31, 2023			5
Balance as of end of period at Mar. 31, 2023		$ 38,565	$ 1,885	[1]	$ 20,095	(35)	17,610	(990)
Ending balance (in shares) at Mar. 31, 2023					1,874
Beginning balance (in shares) at Sep. 30, 2023		5	5
Balance as of beginning of period at Sep. 30, 2023		$ 38,733	$ 1,698	[4]	$ 20,452	(140)	18,040	(1,317)
Beginning balance (in shares) at Sep. 30, 2023					1,849
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		9,553					9,553
Other comprehensive income (loss)		319						319
VE territory covered losses incurred		(60)				(60)
Recovery through conversion rate adjustment		0	$ (25)			25
Conversion to class A common stock (in shares)			0	[5]	2
Conversion to class A common stock		0	$ (71)		$ 71
Share-based compensation		451			$ 451
Stock issued under equity plans (in shares)					3
Stock issued under equity plans		183			$ 183
Restricted stock and performance-based shares settled in cash for taxes (in shares)					(1)
Restricted stock and performance-based shares settled in cash for taxes		(181)			$ (181)
Cash dividends declared and paid, at a quarterly amount per class A common stock		(2,120)					(2,120)
Repurchase of class A common stock (in shares)					(25)
Repurchase of class A common stock		$ (6,393)			$ (267)		(6,126)
Ending balance (in shares) at Mar. 31, 2024		5	5
Balance as of end of period at Mar. 31, 2024		$ 40,485	$ 1,602	[4]	$ 20,709	(175)	19,347	(998)
Ending balance (in shares) at Mar. 31, 2024					1,828
Beginning balance (in shares) at Dec. 31, 2023			5
Balance as of beginning of period at Dec. 31, 2023		39,733	$ 1,615		$ 20,490	(139)	18,422	(655)
Beginning balance (in shares) at Dec. 31, 2023					1,836
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		4,663					4,663
Other comprehensive income (loss)		(343)						(343)
VE territory covered losses incurred		(36)				(36)
Conversion to class A common stock (in shares)			0	[6]	1
Conversion to class A common stock		0	$ (13)		$ 13
Share-based compensation		242			$ 242
Stock issued under equity plans (in shares)					1
Stock issued under equity plans		79			$ 79
Restricted stock and performance-based shares settled in cash for taxes (in shares)	[6]				0
Restricted stock and performance-based shares settled in cash for taxes		(9)			$ (9)
Cash dividends declared and paid, at a quarterly amount per class A common stock		(1,060)					(1,060)
Repurchase of class A common stock (in shares)					(10)
Repurchase of class A common stock		$ (2,784)			$ (106)		(2,678)
Ending balance (in shares) at Mar. 31, 2024		5	5
Balance as of end of period at Mar. 31, 2024		$ 40,485	$ 1,602	[4]	$ 20,709	$ (175)	$ 19,347	$ (998)
Ending balance (in shares) at Mar. 31, 2024					1,828

[1] As of March 31, 2023 and September 30, 2022, the book value of series A preferred stock was $627 million and $1.0 billion, respectively. Refer to Note 5—U.S. and Europe Retrospective Responsibility Plans for the book value of series B and series C preferred stock.

[2] Increase or decrease is less than one million shares.

[3] Increase or decrease is less than one million shares.

[4] As of March 31, 2024 and September 30, 2023, the book value of series A preferred stock was $385 million and $456 million, respectively. Refer to Note 5—U.S. and Europe Retrospective Responsibility Plans for the book value of series B and series C preferred stock

[5] Increase or decrease is less than one million shares.

[6] Increase or decrease is less than one million shares.