Stockholders' Equity - Changes in Stockholders Equity (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Mar. 31, 2025	Mar. 31, 2024
Changes in Stockholders' Equity
Beginning balance	$ 285,970	$ 201,875	$ 216,661
Other comprehensive income (loss)	(880)	(558)
Net income	17,127	10,431	65,944	$ 37,684
Ending balance	305,867	216,661	305,867	216,661
Common stock
Changes in Stockholders' Equity
Beginning balance	111	109	109
Ending balance	111	109	111	109
Treasury stock
Changes in Stockholders' Equity
Beginning balance	(7,837)	(7,837)	(7,837)
Ending balance	(7,837)	(7,837)	(7,837)	(7,837)
Additional paid-in capital
Changes in Stockholders' Equity
Beginning balance	120,864	99,025	103,938
Stock-based compensation and issuance of employee benefit plan stock	3,650	4,913
Ending balance	124,514	103,938	124,514	103,938
Accumulated other comprehensive income (loss)
Changes in Stockholders' Equity
Beginning balance	(34)	(3,040)	(3,598)
Other comprehensive income (loss)	(880)	(558)
Ending balance	(914)	(3,598)	(914)	(3,598)
Retained earnings
Changes in Stockholders' Equity
Beginning balance	172,866	113,618	124,049
Net income	17,127	10,431
Ending balance	$ 189,993	$ 124,049	$ 189,993	$ 124,049