Common Stock, Dividends, Per Share, Declared, Next Fiscal Year, Period Four

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Common Stock, Dividends, Per Share, Declared, Next Fiscal Year, Period Three

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Common Stock, Dividends, Per Share, Declared, Next Fiscal Year, Period Two

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Dividends Declared, Number Of Quarters

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Aggregate dividends paid during the period for each share of common stock outstanding.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

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Aggregate dividends declared during the period for each share of common stock outstanding.

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Cash outflow in the form of capital distributions and dividends to common shareholders, preferred shareholders and noncontrolling interests.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

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-Name Accounting Standards Codification

-Topic 230

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Number of shares that have been repurchased and retired during the period.

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-Name Regulation S-X (SX)

-Number 210

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-Section 02

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Equity impact of the value of stock that has been repurchased and retired during the period. The excess of the purchase price over par value can be charged against retained earnings (once the excess is fully allocated to additional paid in capital).

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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-Name Regulation S-X (SX)

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Amount of stock repurchase plan authorized.

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Amount remaining of a stock repurchase plan authorized.

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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Common Stock Repurchases and Common Stock Dividend) (Details) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	1 Months Ended			3 Months Ended					12 Months Ended
	Jan. 31, 2015	Apr. 30, 2014	Oct. 31, 2013 quarters	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2014	Oct. 31, 2012
Class of Stock [Line Items]
Stock Repurchase Program, Remaining Authorized Repurchase Amount				$ 22,900,000
Common Stock, Dividends, Per Share, Declared	$ 0.12	$ 0.12	$ 0.10
Payments of dividends (per share)				$ 0.12	$ 0.12	$ 0.12	$ 0.1	$ 0.1
Common Stock, Dividends, Per Share, Declared, Next Fiscal Year, Period Two	$ 0.12
Common Stock, Dividends, Per Share, Declared, Next Fiscal Year, Period Three	$ 0.12
Common Stock, Dividends, Per Share, Declared, Next Fiscal Year, Period Four	$ 0.12
Payments of dividends				3,519,000us-gaap_PaymentsOfDividends	3,500,000us-gaap_PaymentsOfDividends	3,600,000us-gaap_PaymentsOfDividends	3,000,000us-gaap_PaymentsOfDividends	3,033,000us-gaap_PaymentsOfDividends
Dividends declared, number of quarters			4powi_DividendsDeclaredNumberOfQuarters
Stock Repurchased and Retired During Period, Shares				0					1.6
Stock Repurchased and Retired During Period, Value				800,000					80,800,000
Common Stock [Member]
Class of Stock [Line Items]
Stock Repurchase Program, Authorized Amount					$ 75,000,000				$ 75,000,000	$ 50,000,000