XML 47 R36.htm IDEA: XBRL DOCUMENT
v3.10.0.1

MARKETABLE SECURITITES Marketable Securities (Details) - USD ($) $ in Thousands | Sep. 30, 2018 | Dec. 31, 2017
--- | --- | ---
Schedule of Available-for-sale Securities [Line Items] |  |
Amortized Cost | $ 100,040 | $ 189,663
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (274) | (427)
Estimated Fair Market Value | 99,766 | 189,236
Investments due in 3 months or less: |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Amortized Cost | 10,038 | 38,485
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (2) | (16)
Estimated Fair Market Value | 10,036 | 38,469
Investments due in 4-12 months: |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Amortized Cost | 65,942 | 113,742
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (250) | (216)
Estimated Fair Market Value | 65,692 | 113,526
Investments due in 12 months or greater: |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Amortized Cost | 24,060 | 37,436
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (22) | (195)
Estimated Fair Market Value | 24,038 | 37,241
Commercial paper | Investments due in 3 months or less: |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Amortized Cost | 5,687 |
Gross Unrealized Gains | 0 |
Gross Unrealized Losses | 0 |
Estimated Fair Market Value | 5,687 |
Corporate securities | Investments due in 3 months or less: |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Amortized Cost | 4,351 | 38,485
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (2) | (16)
Estimated Fair Market Value | 4,349 | 38,469
Corporate securities | Investments due in 4-12 months: |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Amortized Cost | 65,942 | 104,440
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (250) | (199)
Estimated Fair Market Value | 65,692 | 104,241
Corporate securities | Investments due in 12 months or greater: |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Amortized Cost | 24,060 | 37,436
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (22) | (195)
Estimated Fair Market Value | $ 24,038 | 37,241
Government securities | Investments due in 4-12 months: |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Amortized Cost |  | 9,302
Gross Unrealized Gains |  | 0
Gross Unrealized Losses |  | (17)
Estimated Fair Market Value |  | $ 9,285

X
- Definition Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 25 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=75030427&loc=d3e22054-111558 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27232-111563 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=82896770&loc=d3e26610-111562 + Details
Name: | us-gaap_AvailableForSaleSecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563 + Details
Name: | us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563 + Details
Name: | us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.2) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_AvailableForSaleSecuritiesAmortizedCost
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_InvestmentTypeAxis=powi_ShorttermInvestmentsDueinLessThanThreeMonthsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_ShortTermInvestmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_OtherLongTermInvestmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_CommercialPaperMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_ForeignGovernmentDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |