Acquisition Pro Forma Information (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011
Acquisition [Abstract]
Pro forma revenues	$ 250,727	$ 172,256
Pro forma total operating costs and expenses	170,953	159,674
Pro forma operating income	79,774	12,582
Pro forma interest and investment income	937	96
Pro forma income from operations before provision for income taxes	80,711	12,678
Pro forma provision for income taxes	(22,060)	(8,708)
Pro forma net income including noncontrolling interests	58,651	3,970
Pro forma net (income) loss attributable to noncontrolling interests	164	(539)
Pro forma net income attributable to Acacia Research Corporation	$ 58,815	$ 3,431
Pro forma income per common share attributable to Acacia Research Corporation [Abstract]
Pro forma basic earnings per share	$ 1.24	$ 0.09
Pro forma diluted earnings per share	$ 1.22	$ 0.08
Pro forma weighted average number of shares outstanding, basic	47,251,061	39,743,433
Pro forma weighted average number of shares outstanding, diluted	48,060,647	41,258,297

Name:	actg_AcquisitionAbstract
Namespace Prefix:	actg_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Business Acquisition, Pro Forma Income from Operations Before Provision for Income Taxes

+ References

No definition available.

+ Details

Name:	actg_BusinessAcquisitionProFormaIncomeFromOperationsBeforeProvisionForIncomeTaxes
Namespace Prefix:	actg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Business Acquisition, Pro Forma Net Income Including Noncontrolling Interests

+ References

No definition available.

+ Details

Name:	actg_BusinessAcquisitionProFormaNetIncomeIncludingNoncontrollingInterests
Namespace Prefix:	actg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Business Acquisition, Pro Forma Net (Income) Loss Attributable to Noncontrolling Interests

+ References

No definition available.

+ Details

Name:	actg_BusinessAcquisitionProFormaNetIncomeLossAttributableToNoncontrollingInterests
Namespace Prefix:	actg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Business Acquisition, Pro Forma Operating Costs and Expenses

+ References

No definition available.

+ Details

Name:	actg_BusinessAcquisitionProFormaOperatingCostsAndExpenses
Namespace Prefix:	actg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Business Acquisition, Pro Forma Operating Income

+ References

No definition available.

+ Details

Name:	actg_BusinessAcquisitionProFormaOperatingIncome
Namespace Prefix:	actg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Business Acquisition, Pro Forma Other Income

+ References

No definition available.

+ Details

Name:	actg_BusinessAcquisitionProFormaOtherIncome
Namespace Prefix:	actg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Business Acquisition, Pro Forma Provision for Income Taxes

+ References

No definition available.

+ Details

Name:	actg_BusinessAcquisitionProFormaProvisionForIncomeTaxes
Namespace Prefix:	actg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Business Acquisition, Pro Forma Weighted Average Number of Shares, Basic

+ References

No definition available.

+ Details

Name:	actg_BusinessAcquisitionProFormaWeightedAverageNumberOfSharesBasic
Namespace Prefix:	actg_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Business Acquisition, Pro Forma Weighted Average Number of Shares, Diluted

+ References

No definition available.

+ Details

Name:	actg_BusinessAcquisitionProFormaWeightedAverageNumberOfSharesDiluted
Namespace Prefix:	actg_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The pro forma basic net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (h)(2)-(3)

-URI http://asc.fasb.org/extlink&oid=7659399&loc=d3e1392-128463

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141

-Paragraph 54

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141

-Paragraph 55

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141R

-Paragraph 68

-Subparagraph r(2, 3)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Name:	us-gaap_BusinessAcquisitionProFormaEarningsPerShareBasic
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

The pro forma diluted net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

+ References

+ Details

Name:	us-gaap_BusinessAcquisitionProFormaEarningsPerShareDiluted
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period.

+ References

+ Details

Name:	us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The pro forma revenue for a period as if the business combination or combinations had been completed at the beginning of the period.

+ References

+ Details

Name:	us-gaap_BusinessAcquisitionsProFormaRevenue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_EarningsPerShareProFormaAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration