Cost of the investment.

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Name:	us-gaap_InvestmentOwnedAtCost
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Fair Value Measurements - Additional Information (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Jun. 30, 2026 USD ($)	Jun. 30, 2026 USD ($)	Jun. 30, 2025 USD ($)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment for solar energy project		$ 50,146	$ 0
Solar energy equity investment
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment for solar energy project		50,100
Investment	$ 184,700	184,700
Amount paid	184,700	184,700
Unamortized balance of Investment	113,100	113,100
Solar energy equity investment \| Location, Statement of Financial Position, Balance [Axis]: us-gaap:OtherLiabilitiesNoncurrent
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment commitments LT	21,100	21,100
Solar energy equity investment \| Location, Statement of Financial Position, Balance [Axis]: ptc:AccruedExpensesAndOtherLiabilityCurrent
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment commitments ST	$ 113,500	$ 113,500
Solar energy equity investment \| Maximum
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Contingent deficit restoration obligation	0.55