Stockholders' Equity - Changes in Stockholders Equity (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023
Changes in Stockholders' Equity
Beginning balance	$ 201,875	$ 146,043	$ 154,526	$ 146,043
Other comprehensive income (loss)	(558)	514
Net income	10,431	3,172	37,684		$ 4,294
Ending balance	216,661	154,526	216,661	201,875	154,526
Common stock
Changes in Stockholders' Equity
Beginning balance	109	108	108	108
Ending balance	109	108	109	109	108
Treasury stock
Changes in Stockholders' Equity
Beginning balance	(7,837)	(7,837)	(7,837)	(7,837)
Ending balance	(7,837)	(7,837)	(7,837)	(7,837)	(7,837)
Additional paid-in capital
Changes in Stockholders' Equity
Beginning balance	99,025	75,066	79,863	75,066
Stock-based compensation and issuance of employee benefit plan stock	4,913	4,797
Ending balance	103,938	79,863	103,938	99,025	79,863
Accumulated other comprehensive income (loss)
Changes in Stockholders' Equity
Beginning balance	(3,040)	(4,487)	(3,973)	(4,487)
Other comprehensive income (loss)	(558)	514
Ending balance	(3,598)	(3,973)	(3,598)	(3,040)	(3,973)
Retained earnings
Changes in Stockholders' Equity
Beginning balance	113,618	83,193	86,365	83,193
Net income	10,431	3,172
Ending balance	$ 124,049	$ 86,365	$ 124,049	$ 113,618	$ 86,365