CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (UNAUDITED) - USD ($) shares in Millions, $ in Millions		Total	Conversion of series A preferred stock upon sales into public market	Conversion of class C common stock upon sales into public market	Cumulative Effect, Period of Adoption, Adjustment	Series B preferred stock	Series C preferred stock	Class A common stock	Preferred Stock	Preferred Stock Conversion of series A preferred stock upon sales into public market	Preferred Stock Series A preferred stock	[1]	Preferred Stock Series A preferred stock Conversion of series A preferred stock upon sales into public market		Preferred Stock Series B preferred stock	Preferred Stock Series C preferred stock	Common Stock Class A common stock	Common Stock Class A common stock Conversion of series A preferred stock upon sales into public market	Common Stock Class A common stock Conversion of class C common stock upon sales into public market		Common Stock Class B common stock	Common Stock Class C common stock	Common Stock Class C common stock Conversion of class C common stock upon sales into public market		Right to Recover for Covered Losses	Additional Paid-In Capital	Additional Paid-In Capital Conversion of series A preferred stock upon sales into public market	Accumulated Income	Accumulated Income Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Income (Loss), Net
Beginning balance (for Series A Preferred Stock, less than one million shares) (in shares) at Sep. 30, 2020											0				2	3	1,683				245	11
Beginning balance at Sep. 30, 2020		$ 36,210			$ 3				$ 5,086						$ 1,106	$ 1,543									$ (39)	$ 16,721		$ 14,088	$ 3	$ 354
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		6,152																										6,152
Other comprehensive income (loss), net of tax		18																												18
Comprehensive income		6,170
VE territory covered losses incurred		(17)													0	0									(17)
Recovery through conversion rate adjustment		0				$ 9	$ 6		(15)						$ (9)	$ (6)									15
Conversion of stock (for Series A Preferred Stock, less than one million shares) (in shares)													0	[1]				25	0	[1]			0	[1]
Conversion of stock			$ 0							$ (1,724)																	$ 1,724
Share-based compensation, net of forfeitures		275																								275
Vesting of restricted stock and performance-based shares (in shares)																	3
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		(140)																								(140)
Cash proceeds from issuance of class A common stock under employee equity plans (in shares)																	1
Cash proceeds from issuance of class A common stock under employee equity plans		108																								108
Cash dividends declared and paid, at a quarterly amount per Class A share		(1,404)																										(1,404)
Repurchase of class A common stock (in shares)								(17)									(17)
Repurchase of class A common stock		(3,509)						$ (3,509)																		(183)		(3,326)
Ending balance (for Series A Preferred Stock, less than one million shares) (in shares) at Mar. 31, 2021											0				2	3	1,694				245	11
Ending balance at Mar. 31, 2021		37,696							3,347						$ 1,097	$ 1,537									(41)	18,505		15,513		372
Beginning balance (for Series A Preferred Stock, less than one million shares) (in shares) at Dec. 31, 2020											0				2	3	1,696				245	11
Beginning balance at Dec. 31, 2020		37,679							3,683																(34)	18,063		14,813		1,154
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		3,026																										3,026
Other comprehensive income (loss), net of tax		(782)																												(782)
Comprehensive income		2,244
VE territory covered losses incurred		(7)																							(7)
Conversion of stock (for Series A Preferred Stock, less than one million shares) (in shares)													0	[1]				5	0	[1]			0	[1]
Conversion of stock			0							(336)																	336
Share-based compensation, net of forfeitures		153																								153
Vesting of restricted stock and performance-based shares (in shares)	[1]																0
Restricted stock and performance-based shares settled in cash for taxes (in shares)	[1]																0
Restricted stock and performance-based shares settled in cash for taxes		(6)																								(6)
Cash proceeds from issuance of class A common stock under employee equity plans (in shares)																	1
Cash proceeds from issuance of class A common stock under employee equity plans		47																								47
Cash dividends declared and paid, at a quarterly amount per Class A share		(701)																										(701)
Repurchase of class A common stock (in shares)								(8)									(8)
Repurchase of class A common stock		(1,713)						$ (1,713)																		(88)		(1,625)
Ending balance (for Series A Preferred Stock, less than one million shares) (in shares) at Mar. 31, 2021											0				2	3	1,694				245	11
Ending balance at Mar. 31, 2021		37,696							3,347						$ 1,097	$ 1,537									(41)	18,505		15,513		372
Beginning balance (for Series A Preferred Stock, less than one million shares) (in shares) at Sep. 30, 2021											0				2	3	1,677				245	10
Beginning balance at Sep. 30, 2021		37,589							3,080						$ 1,071	$ 1,523									(133)	18,855		15,351		436
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		7,606																										7,606
Other comprehensive income (loss), net of tax		(841)																												(841)
Comprehensive income		6,765
VE territory covered losses incurred		(16)													0	0									(16)
Recovery through conversion rate adjustment		0				$ 26	$ 3		(29)						$ (26)	$ (3)									29
Conversion of stock (for Series A Preferred Stock, less than one million shares) (in shares)													0	[1]				1	0	[1]			0	[1]
Conversion of stock			0	$ 0						(64)																	64
Share-based compensation, net of forfeitures		318																								318
Vesting of restricted stock and performance-based shares (in shares)																	2
Restricted stock and performance-based shares settled in cash for taxes (in shares)	[1]																0
Restricted stock and performance-based shares settled in cash for taxes		(116)																								(116)
Cash proceeds from issuance of class A common stock under employee equity plans (in shares)																	2
Cash proceeds from issuance of class A common stock under employee equity plans		113																								113
Cash dividends declared and paid, at a quarterly amount per Class A share		(1,611)																										(1,611)
Repurchase of class A common stock (in shares)								(34)									(34)
Repurchase of class A common stock		(7,053)						$ (7,053)																		(358)		(6,695)
Ending balance (for Series A Preferred Stock, less than one million shares) (in shares) at Mar. 31, 2022											0				2	3	1,648				245	10
Ending balance at Mar. 31, 2022		35,989							2,987						$ 1,045	$ 1,520									(120)	18,876		14,651		(405)
Beginning balance (for Series A Preferred Stock, less than one million shares) (in shares) at Dec. 31, 2021											0				2	3	1,661				245	10
Beginning balance at Dec. 31, 2021		36,194							2,995																(111)	18,776		14,606		(72)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		3,647																										3,647
Other comprehensive income (loss), net of tax		(333)																												(333)
Comprehensive income		3,314
VE territory covered losses incurred		(9)																							(9)
Conversion of stock (for Series A Preferred Stock, less than one million shares) (in shares)	[1]												0					0	0				0
Conversion of stock			$ 0	$ 0						$ (8)																	$ 8
Share-based compensation, net of forfeitures		190																								190
Vesting of restricted stock and performance-based shares (in shares)	[1]																0
Restricted stock and performance-based shares settled in cash for taxes (in shares)	[1]																0
Restricted stock and performance-based shares settled in cash for taxes		(3)																								(3)
Cash proceeds from issuance of class A common stock under employee equity plans (in shares)																	2
Cash proceeds from issuance of class A common stock under employee equity plans		54																								54
Cash dividends declared and paid, at a quarterly amount per Class A share		(802)																										(802)
Repurchase of class A common stock (in shares)								(15)									(15)
Repurchase of class A common stock		(2,949)						$ (2,949)																		(149)		(2,800)
Ending balance (for Series A Preferred Stock, less than one million shares) (in shares) at Mar. 31, 2022											0				2	3	1,648				245	10
Ending balance at Mar. 31, 2022		$ 35,989							$ 2,987						$ 1,045	$ 1,520									$ (120)	$ 18,876		$ 14,651		$ (405)

[1] Increase, decrease or balance is less than one million shares.