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Name:	powi_StockholdersEquityLineItems
Namespace Prefix:	powi_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

STOCKHOLDERS' EQUITY Common Stock Repurchases (Details) - USD ($) $ in Millions	Apr. 27, 2021	Mar. 31, 2021
Stockholders' Equity [Line Items]
Stock Repurchase Program, Remaining Authorized Repurchase Amount		$ 41.3
Subsequent Event
Stockholders' Equity [Line Items]
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 50.0