Long-term Debt (Interest rate swaps) (Details 2)	Oct. 04, 2015 USD ($)	Oct. 04, 2015 EUR (€)
Long-Term Debt
Notional amount \| €		€ 16,062
Notional amount to mature August 2016
Long-Term Debt
Notional amount	$ 100,000,000
Derivative at fair value	$ (466,000)
Derivative, fixed interest rate	0.87%	0.87%
Derivative, variable interest rate	0.19%	0.19%
Notional amount to mature August 2017
Long-Term Debt
Notional amount	$ 100,000,000
Derivative at fair value	$ (1,421,000)
Derivative, fixed interest rate	1.29%	1.29%
Derivative, variable interest rate	0.19%	0.19%
Notional amount to mature August 2018
Long-Term Debt
Notional amount	$ 100,000,000
Derivative at fair value	$ (2,670,000)
Derivative, fixed interest rate	1.69%	1.69%
Derivative, variable interest rate	0.19%	0.19%
Notional amount to mature November 2016
Long-Term Debt
Notional amount	$ 50,000,000
Derivative at fair value	$ (148,000)
Derivative, fixed interest rate	0.65%	0.65%
Derivative, variable interest rate	0.19%	0.19%
Notional amount to mature November 2017
Long-Term Debt
Notional amount	$ 50,000,000
Derivative at fair value	$ (540,000)
Derivative, fixed interest rate	1.10%	1.10%
Derivative, variable interest rate	0.19%	0.19%

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 12

-Section 13

-Sentence Column B

+ Details

Name:	invest_DerivativeNotionalAmount
Namespace Prefix:	invest_
Data Type:	xbrli:monetaryItemType
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

Fixed interest rate related to the interest rate derivative.

+ References

No definition available.

+ Details

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

- Definition

Variable interest rate in effect as of the balance sheet date related to the interest rate derivative.

+ References

No definition available.

+ Details

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

- Definition

Fair value as of the balance sheet date of all interest rate derivatives designated as cash flow hedging instruments.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 45

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958

+ Details

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

- Details

Name:	us-gaap_DerivativeByNatureAxis=atk_NotionalamounttomatureAugust2016Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeByNatureAxis=atk_NotionalamounttomatureAugust2017Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeByNatureAxis=atk_NotionalamounttomatureAugust2018Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeByNatureAxis=atk_NotionalamounttomatureNovember2016Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeByNatureAxis=atk_NotionalamounttomatureNovember2017Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: