Summary of Significant Accounting Policies and Other Information - Narrative (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2025 USD ($) boardMember	Sep. 30, 2024 USD ($)	Sep. 30, 2025 USD ($) segment boardMember	Sep. 30, 2024 USD ($)	Sep. 18, 2025	Jul. 30, 2025 USD ($)	Dec. 31, 2024 USD ($)	Aug. 30, 2024 USD ($)
Concentration Risk [Line Items]
Number of board members | boardMember	4		4
Net income	$ 27,616,000	$ 17,337,000	$ 97,910,000	$ 45,992,000
Cash flow from operating activities			$ 28,730,000	29,739,000
Number of operating segments | segment			1
Restricted cash	3,680,000	$ 3,217,000	$ 3,680,000	$ 3,217,000			$ 3,239,000
Inventory raw materials provided by customers	$ 2,800,000		$ 2,800,000
Weichai America Corp | Power Solutions International, Inc.
Concentration Risk [Line Items]
Equity method investment, ownership percentage	46.50%		46.50%
Founders | Power Solutions International, Inc.
Concentration Risk [Line Items]
Beneficial ownership percentage					6.30%
Line of Credit | Revolving Credit Facility | Revolving Credit Agreement
Concentration Risk [Line Items]
Maximum borrowing capacity (upto)						$ 135,000,000		$ 120,000,000.0
Contract With Customer
Concentration Risk [Line Items]
Restricted cash	$ 1,400,000		$ 1,400,000				$ 1,400,000