Percentage of financial targets to be achieved for participants to receive award.

No definition available.

Name:	acta_PercentageOfFinancialTargetsToBeAchievedForParticipantsToReceiveAward
Namespace Prefix:	acta_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Performance Plan Achievement Percentage

+ References

No definition available.

+ Details

Name:	acta_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsPerformancePlanAchievementPercentage
Namespace Prefix:	acta_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(3)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(1)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(2)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(2)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

+ Details

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

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

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_RestrictedStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=acta_PerformanceBasedPlanTwoThousandFifteenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=acta_PerformanceBasedPlanTwoThousandSixteenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=acta_PerformanceBasedPlanTwoThousandSeventeenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Equity-Based Compensation - Restricted Stock Awards with Performance Conditions (Details) - $ / shares	3 Months Ended				6 Months Ended	12 Months Ended
	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2016	Mar. 31, 2016	Jun. 30, 2017	Dec. 31, 2016	Dec. 31, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted Shares Forfeited (in shares)			15,000
Restricted stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
ACTA Stock Price at Issuance (in dollars per share)	$ 9.66	$ 15.30	$ 13.33	$ 18.75
Restricted Shares Granted (in shares)	54,310	286,256	112,397	434,283
Restricted Shares Vested (in shares)	81,897	625,646	81,391	657,317
Restricted Shares Forfeited (in shares)		167,712	7,500	588,819
Actua 2015 Performance Plan \| Restricted stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of Target Bonus Potentially Payable in Restricted Stock							150.00%
ACTA Stock Price at Issuance (in dollars per share)							$ 16.76
Restricted Shares Granted (in shares)							316,715
Performance Plan Achievement Percentage							83.00%
Restricted Shares Vested (in shares)							175,249
Restricted Shares Forfeited (in shares)							141,466
Actua 2016 Performance Plan \| Restricted stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of Target Bonus Potentially Payable in Restricted Stock						100.00%
ACTA Stock Price at Issuance (in dollars per share)						$ 8.44
Restricted Shares Granted (in shares)						419,283
Performance Plan Achievement Percentage						60.00%
Restricted Shares Vested (in shares)						251,570
Restricted Shares Forfeited (in shares)						167,713
Actua 2017 Performance Plan \| Restricted stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of Target Bonus Potentially Payable in Restricted Stock					100.00%
ACTA Stock Price at Issuance (in dollars per share)					$ 13.85
Restricted Shares Granted (in shares)					263,756