Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.F)
-URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(i)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

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

- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ 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 (a)(1)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- 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=6415400&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=6415400&loc=d3e5070-113901

+ Details

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

- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued 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=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
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=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
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

- Definition

Net number of non-option equity instruments granted to participants.

+ 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)(1)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
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_NonManagementDirectorsDirectorPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

Name:	us-gaap_VestingAxis=us-gaap_ShareBasedCompensationAwardTrancheOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VestingAxis=us-gaap_ShareBasedCompensationAwardTrancheTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

Equity-Based Compensation - The Amended Director Plan Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended
	Jun. 30, 2015	Mar. 31, 2017	Mar. 31, 2016
Restricted stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares, vested (in shares)		625,646	657,317
Number of shares granted (in shares)		286,256	434,283
Grant date fair value (in dollars per share)		$ 13.85	$ 8.44
Number of shares, forfeited (in shares)		167,712	588,819
Restricted stock \| Non-Management Director Compensation Plan (the Director Plan)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock awards vesting period		6 months
Restricted stock \| Non Management Directors Director Plan, Retainer Fee, June 12, 2015 through June 12, 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares granted (in shares)	50,416
Grant date fair value (in dollars per share)	$ 13.17
Restricted stock \| Non Management Directors Director Plan, Triennial Service Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares granted (in shares)	90,000
Grant date fair value (in dollars per share)	$ 13.17
Restricted stock \| Non Management Directors Director Plan, Triennial Service Awards \| Tranche one
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares granted (in shares)		52,500
Restricted stock \| Non Management Directors Director Plan, Triennial Service Awards \| Vested in equal increments from June 2017 through June 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares granted (in shares)		37,500
Deferred Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based compensation expense		$ 0.1	$ 0.1
Deferred Stock Units \| Non-Management Director Compensation Plan (the Director Plan)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of non-option shares, granted (in shares)		22,500
Number of shares, vested (in shares)		5,625
Deferred Stock Units \| Non-Management Director Compensation Plan (the Director Plan) \| Tranche one
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock awards vesting period		1 year
Number of shares, vested (in shares)		7,500
Deferred Stock Units \| Non-Management Director Compensation Plan (the Director Plan) \| Vested in equal increments from June 2017 through June 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock awards vesting period		2 years
Number of shares, vested (in shares)		15,000
Deferred Stock Units \| Prior Director Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of non-option shares, granted (in shares)		7,500
Deferred Stock Units \| Non Management Directors Director Plan, Triennial Service Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares granted (in shares)	90,000
Grant date fair value (in dollars per share)	$ 13.17
Deferred Stock Units \| Non Management Directors Director Plan, Triennial Service Awards \| Tranche one
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares granted (in shares)		46,875
Number of shares, forfeited (in shares)		15,000
Deferred Stock Units \| Non Management Directors Director Plan, Triennial Service Awards \| Vested in equal increments from June 2017 through June 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares granted (in shares)		28,125