Debt Instrument, Unused Borrowing Capacity Available for Borrowing, Amount

No definition available.

Name:	atu_DebtInstrumentUnusedBorrowingCapacityAvailableforBorrowingAmount
Namespace Prefix:	atu_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Interest coverage ratio

+ References

No definition available.

+ Details

Name:	atu_Interestcoverageratio
Namespace Prefix:	atu_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Definition

Leverage ratio.

+ References

No definition available.

+ Details

Name:	atu_LeverageRatio
Namespace Prefix:	atu_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Definition

Line of credit facility additional expansion option available

+ References

No definition available.

+ Details

Name:	atu_LineOfCreditFacilityAdditionalExpansionOptionAvailable
Namespace Prefix:	atu_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=34725769&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ 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 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

+ Details

Name:	us-gaap_DebtInstrumentInterestRateEffectivePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

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

- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

+ Details

Name:	us-gaap_DebtInstrumentMaturityDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of the required periodic payments applied to principal.

+ References

+ Details

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

- Definition

Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph e
-URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823

+ Details

Name:	us-gaap_DebtInstrumentRedemptionPricePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of unused borrowing capacity under the long-term financing arrangement that is available to the entity as of the balance sheet date.

+ References

+ Details

Name:	us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=atu_SeniorCreditFacilityTermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_LineOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=atu_SeniorCreditFacilityRevolverMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=atu_FivePointSixTwoFiveSeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_BaseRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	atu_PeriodAxis=atu_PeriodOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementScenarioAxis=us-gaap_ScenarioForecastMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	atu_PeriodAxis=atu_PeriodtwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Debt - Additional Information (Details)				3 Months Ended	6 Months Ended
Debt - Additional Information (Details)	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Apr. 16, 2012 USD ($)	Feb. 29, 2016 USD ($)	Feb. 29, 2016 USD ($)
Debt Instrument [Line Items]
Senior credit facility expansion option, available				$ 450,000,000	$ 450,000,000
Debt Instrument, actual interest rate				2.19%	2.19%
Libor Rate
Debt Instrument [Line Items]
Debt instrument, interest rate over variable rate				1.75%
Revolving Credit Facility
Debt Instrument [Line Items]
Debt Instrument, Maturity Date					May 08, 2020
Maximum borrowing capacity				$ 600,000,000	$ 600,000,000
Senior Credit Facility - Term Loan
Debt Instrument [Line Items]
Maximum borrowing capacity				300,000,000	300,000,000
Line of Credit \| Senior Credit Facility - Revolver
Debt Instrument [Line Items]
Unused credit line				588,600,000	588,600,000
Unused credit line Available for Borrowing, Amount				$ 217,600,000	$ 217,600,000
Senior Notes \| 5.625% Senior Notes
Debt Instrument [Line Items]
Debt Instrument, Maturity Date					Jun. 15, 2022
Debt Instrument, Face Amount			$ 300,000,000
Debt instrument, interest rate			5.625%
Minimum
Debt Instrument [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage				0.15%
Interest coverage ratio				3.5	3.5
Minimum \| Libor Rate
Debt Instrument [Line Items]
Debt instrument, interest rate over variable rate				1.00%
Minimum \| Base Rate
Debt Instrument [Line Items]
Debt instrument, interest rate over variable rate				0.00%
Minimum \| Senior Notes \| 5.625% Senior Notes
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage			100.00%
Maximum
Debt Instrument [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage				0.35%
Leverage ratio				3.75	3.75
Maximum \| Libor Rate
Debt Instrument [Line Items]
Debt instrument, interest rate over variable rate				2.25%
Maximum \| Base Rate
Debt Instrument [Line Items]
Debt instrument, interest rate over variable rate				1.25%
Maximum \| Senior Notes \| 5.625% Senior Notes
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage			102.80%
Starting on June 30, 2016 \| Scenario, Forecast \| Senior Credit Facility - Term Loan
Debt Instrument [Line Items]
Quarterly installments, payable on term loan		$ 3,750,000
Starting on June 30, 2017 \| Scenario, Forecast \| Senior Credit Facility - Term Loan
Debt Instrument [Line Items]
Quarterly installments, payable on term loan	$ 7,500,000