The consideration before closing adjustment for a disposal group held for sale or disposed of.

No definition available.

Name:	sigm_DisposalGroupIncludingDiscontinuedOperationConsiderationBeforeClosingAdjustment
Namespace Prefix:	sigm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of estimated distributions to shareholders pursuant to the liquidation plan.

+ References

No definition available.

+ Details

Name:	sigm_LiquidationBasisOfAccountingAnticipateAmountOfAggregateDistributionsToShareholders
Namespace Prefix:	sigm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the amount held in escrow included in the aggregate cash proceeds received from a combination of transactions in which noncurrent assets are sold, which may include the sale of a business, an investment in an affiliate (including an equity method investee), property, plant and equipment and intangible assets. Excludes sales of trading, available-for-sale, and held-to-maturity securities.

+ References

No definition available.

+ Details

Name:	sigm_SaleOfBusinessAmountHeldInEscrow
Namespace Prefix:	sigm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Deduction for fluctuations in working capital included in the calculation of the aggregate cash proceeds received from a combination of transactions in which noncurrent assets are sold, which may include the sale of a business, an investment in an affiliate (including an equity method investee), property, plant and equipment and intangible assets. Excludes sales of trading, available-for-sale, and held-to-maturity securities.

+ References

No definition available.

+ Details

Name:	sigm_SaleOfBusinessDeductionOfWorkingCapitalFluctuations
Namespace Prefix:	sigm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The amount of working capital that is targeted as of a certain date.

+ References

No definition available.

+ Details

Name:	sigm_TargetWorkingCapital
Namespace Prefix:	sigm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of consideration received or receivable for the disposal of assets and liabilities, including discontinued operation.

+ References

No definition available.

+ Details

Name:	us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash inflow associated with the amount received from the sale of a portion of the company's business, for example a segment, division, branch or other business, during the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3179-108585

+ Details

Name:	us-gaap_ProceedsFromDivestitureOfBusinesses
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=sigm_PurchasedIPMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=sigm_SigmaDesignsIsraelSDILtdMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=sigm_MultimediaBusinessMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=sigm_ZWaveMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Note 1 - Organization and Summary of Significant Accounting Policies (Details Textual) - USD ($)				3 Months Ended
	Apr. 17, 2018	Mar. 21, 2018	Feb. 15, 2018	May 05, 2018
Minimum [Member]
Liquidation Basis of Accounting, Anticipate Amount of Aggregate Distributions to Shareholders	$ 235,000,000
Finite-Lived Intangible Asset, Useful Life				3 years
Minimum [Member] \| Purchased IP [Member]
Finite-Lived Intangible Asset, Useful Life				2 years
Maximum [Member]
Liquidation Basis of Accounting, Anticipate Amount of Aggregate Distributions to Shareholders	255,000,000
Finite-Lived Intangible Asset, Useful Life				10 years
Maximum [Member] \| Purchased IP [Member]
Finite-Lived Intangible Asset, Useful Life				3 years
Sigma Designs Israel S.D.I Ltd. [Member]
Disposal Group, Including Discontinued Operation, Consideration			$ 28,000,000
Proceeds from Divestiture of Businesses			23,500,000
Sale of Business, Deduction of Working Capital Fluctuations			300,000
Sale of Business, Amount Held in Escrow			$ 4,200,000
Multimedia Business [Member]
Proceeds from Divestiture of Businesses		$ 5,300,000
Disposal Group, Including Discontinued Operation, Consideration before Closing Adjustment		5,000,000
Target Working Capital		$ 2,500,000
Z-Wave [Member]
Proceeds from Divestiture of Businesses	$ 240,000,000