Weichai Transactions - Weichai Collaboration Arrangement (Details) - USD ($) $ in Millions		12 Months Ended
Mar. 20, 2017	Dec. 31, 2019	Dec. 31, 2018
Equity [Abstract]
Term of collaborative arrangement	3 years
Purchased inventory		$ 4.4	$ 3.5
Outstanding payables		$ 5.9	$ 3.7

Collaborative Arrangement, Inventory, Purchased Goods

No definition available.

Name:	psix_CollaborativeArrangementInventoryPurchasedGoods
Namespace Prefix:	psix_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration