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, 2022			$ 477	$ 57		$ 28,053	$ (1,485)	$ (16,738)	$ 5,952
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock plans				81
AspenTech purchases of common stock					$ 0
Purchases								(2,000)	0
Net earnings common stockholders	$ 3,123					3,123
Dividends paid (per share: $0.520, $0.525, $1.040 and $1.050, respectively)						(605)
Foreign currency translation	351						347
Pension and postretirement	(33)						(33)
Cash flow hedges	23						23
Issued under stock plans								60
Net earnings (loss)									(27)
Stock plans									58
Other comprehensive income	341								4
Stockholders' equity, ending balance at Mar. 31, 2023	17,347	$ 11,360	477	138		30,571	(1,148)	(18,678)	5,987
Stockholders' equity, beginning balance at Dec. 31, 2022			477	112		30,076	(1,255)	(18,683)	5,987
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock plans				26
AspenTech purchases of common stock					0
Purchases								0		$ 0
Net earnings common stockholders	792					792
Dividends paid (per share: $0.520, $0.525, $1.040 and $1.050, respectively)						(297)
Foreign currency translation	110						111
Pension and postretirement	(17)						(17)
Cash flow hedges	13						13
Issued under stock plans								5
Net earnings (loss)									(22)
Stock plans									23
Other comprehensive income	106								(1)
Stockholders' equity, ending balance at Mar. 31, 2023	17,347	11,360	477	138		30,571	(1,148)	(18,678)	5,987
Stockholders' equity, beginning balance at Sep. 30, 2023	26,598		477	62		40,070	(1,253)	(18,667)	5,909
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock plans				170
AspenTech purchases of common stock					(74)
Purchases								(175)	(55)
Net earnings common stockholders	643					643
Dividends paid (per share: $0.520, $0.525, $1.040 and $1.050, respectively)						(605)
Foreign currency translation	180						178
Pension and postretirement	(24)						(24)
Cash flow hedges	2						2
Issued under stock plans								96
Net earnings (loss)									(8)
Stock plans									33
Other comprehensive income	158								2
Stockholders' equity, ending balance at Mar. 31, 2024	26,781	20,900	477	158		40,108	(1,097)	(18,746)	5,881
Stockholders' equity, beginning balance at Dec. 31, 2023			477	140		39,910	(1,090)	(18,763)	5,881
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock plans				51
AspenTech purchases of common stock					$ (33)
Purchases								0		$ (24)
Net earnings common stockholders	501					501
Dividends paid (per share: $0.520, $0.525, $1.040 and $1.050, respectively)						(303)
Foreign currency translation	6						6
Pension and postretirement	(12)						(12)
Cash flow hedges	(1)						(1)
Issued under stock plans								17
Net earnings (loss)									2
Stock plans									22
Other comprehensive income	(7)								0
Stockholders' equity, ending balance at Mar. 31, 2024	$ 26,781	$ 20,900	$ 477	$ 158		$ 40,108	$ (1,097)	$ (18,746)	$ 5,881