Consolidated Statements of Equity - USD ($) $ in Millions	Total	Common stockholders' equity	Common stock	Additional paid-in-capital	Additional paid-in-capital AspenTech	Retained earnings	Accumulated other comprehensive income (loss)	Treasury stock	Noncontrolling interests in subsidiaries	Noncontrolling interests in subsidiaries AspenTech
Stockholders' equity, beginning balance at Sep. 30, 2023			$ 477	$ 62		$ 40,070	$ (1,253)	$ (18,667)	$ 5,909
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock plans				119
AspenTech purchases of common stock					$ (41)
Purchases								(175)		$ (31)
Net earnings common stockholders	$ 142					142
Dividends paid (per share: $0.525 and $0.5275, respectively)						(302)
Foreign currency translation	174						172
Pension and postretirement	(12)						(12)
Cash flow hedges	3						3
Issued under stock plans								79
Net earnings (loss)									(10)
Stock plans									11
Other comprehensive income	165								2
Stockholders' equity, ending balance at Dec. 31, 2023	26,555	$ 20,674	477	140		39,910	(1,090)	(18,763)	5,881
Stockholders' equity, beginning balance at Sep. 30, 2024	27,509		477	169		40,830	(868)	(18,972)	5,873
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock plans				(56)
AspenTech purchases of common stock					$ 0
Purchases								(946)		$ 0
Net earnings common stockholders	585					585
Dividends paid (per share: $0.525 and $0.5275, respectively)						(303)
Foreign currency translation	(492)						(485)
Pension and postretirement	3						3
Cash flow hedges	10						10
Issued under stock plans								46
Net earnings (loss)									8
Stock plans									15
Other comprehensive income	(479)								(7)
Stockholders' equity, ending balance at Dec. 31, 2024	$ 26,379	$ 20,490	$ 477	$ 113		$ 41,112	$ (1,340)	$ (19,872)	$ 5,889