Stockholders' Equity - Changes in Stockholders Equity (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Changes in Stockholders' Equity
Beginning balance	$ 168,602	$ 131,402	$ 146,043	$ 138,245	$ 146,043	$ 138,245	$ 137,489
Common stock repurchased						(6,000)
Other comprehensive income (loss)	(1,323)	(2,333)			(516)	(5,739)
Net income (loss)	9,879	2,872			19,801	(3,000)	20,079	$ 11,323
Ending balance	182,973	137,489	168,602	131,402	182,973	137,489	182,973	137,489
Common stock
Changes in Stockholders' Equity
Beginning balance	108	107	108	106	108	106	107
Stock-based compensation and issuance of employee benefit plan stock	0	0			0	1
Ending balance	108	107	108	107	108	107	108	107
Treasury stock
Changes in Stockholders' Equity
Beginning balance	(7,837)	(7,837)	(7,837)	(1,837)	(7,837)	(1,837)	(7,837)
Common stock repurchased	0	0			0	(6,000)
Ending balance	(7,837)	(7,837)	(7,837)	(7,837)	(7,837)	(7,837)	(7,837)	(7,837)
Additional paid-in capital
Changes in Stockholders' Equity
Beginning balance	86,896	63,871	75,066	55,437	75,066	55,437	69,419
Stock-based compensation and issuance of employee benefit plan stock	5,815	5,548			17,645	13,982
Ending balance	92,711	69,419	86,896	63,871	92,711	69,419	92,711	69,419
Accumulated other comprehensive income (loss)
Changes in Stockholders' Equity
Beginning balance	(3,680)	(4,782)	(4,487)	(1,376)	(4,487)	(1,376)	(7,115)
Other comprehensive income (loss)	(1,323)	(2,333)			(516)	(5,739)
Ending balance	(5,003)	(7,115)	(3,680)	(4,782)	(5,003)	(7,115)	(5,003)	(7,115)
Retained earnings
Changes in Stockholders' Equity
Beginning balance	93,115	80,043	83,193	85,915	83,193	85,915	82,915
Net income (loss)	9,879	2,872			19,801	(3,000)
Ending balance	$ 102,994	$ 82,915	$ 93,115	$ 80,043	$ 102,994	$ 82,915	$ 102,994	$ 82,915