Refers to an additional period of time to issue notes.

No definition available.

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- Definition

Represents the restrictions on investments, change of control provisions and provisions, expressed as a percentage of total assets to be disposed off as per the financial covenant.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Represents the number of annual principal payments of debt instrument required by the entity.

+ References

No definition available.

+ Details

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- Definition

Represents the amount of prepayment to be paid on the debt instrument.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

The annual fee percentage based on any issued and outstanding letters of credit under the facility.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility with the accordion feature.

+ References

No definition available.

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Period Type:	instant

- Definition

Indicates the number of assets pledged under the loan plan.

+ References

No definition available.

+ Details

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- Definition

Represents the number of mortgages assumed.

+ References

No definition available.

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Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of liabilities assumed at the acquisition date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=84161108&loc=d3e4845-128472

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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

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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
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

+ Details

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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

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of the required periodic payments applied to principal.

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Weighted average interest rate of debt outstanding.

+ References

No definition available.

+ Details

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

- Definition

Amount, before accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28555-108399

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-Paragraph 1
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-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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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

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Indicates the number of mortgages under each classification.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 948
-SubTopic 310
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-29.3)
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-Section S99
-Paragraph 6
-Subparagraph (SX 210.5-04.(c) Schedule IV)
-URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674

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Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

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- Details

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Credit Arrangements - Narrative (Details) $ in Millions, $ in Millions				1 Months Ended	6 Months Ended	12 Months Ended
	Nov. 09, 2015 USD ($) payment	Jun. 03, 2015 USD ($)	Jul. 25, 2013 USD ($) payment	Dec. 31, 2015 USD ($) loan building	Jun. 30, 2018 USD ($)	Dec. 31, 2017 USD ($) loan building	Jun. 30, 2018 CAD ($)	Jun. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 29, 2017 USD ($)	Sep. 28, 2017 USD ($)	Dec. 28, 2012 USD ($)	Dec. 27, 2012 USD ($)
Credit arrangements
Weighted average interest rate (as a percent)						3.00%	3.90%	3.90%
Commercial equipment notes \| Minimum
Credit arrangements
Interest rate (as a percent)							1.78%	1.78%
Commercial equipment notes \| Maximum
Credit arrangements
Interest rate (as a percent)							4.40%	4.40%
Mortgages
Credit arrangements
Interest rate (as a percent)						5.00%
Number of assets secured \| building						3
Number of mortgages assumed \| loan						3
Assumed notes						$ 4.2
Secured mortgage notes, maturing on January 1, 2031
Credit arrangements
Interest rate (as a percent)				4.30%
Number of secured mortgage notes payable to a bank \| loan				2
Principal amount				$ 8.0
Number of assets secured \| building				2
Senior secured notes
Credit arrangements
Interest rate (as a percent)	4.60%						3.65%	3.65%
Principal amount	$ 25.0												$ 50.0
Number of annual principal payments \| payment	7
Required principal payment	$ 3.6				$ 7.1
Senior secured notes \| Minimum
Credit arrangements
Prepayment to be paid on debt					$ 5.0
Notes Agreement
Credit arrangements
Interest rate (as a percent)			3.85%
Principal amount			$ 25.0									$ 25.0
Number of annual principal payments \| payment			7
Required principal payment			$ 3.6
Notes Agreement \| Minimum
Credit arrangements
Restrictions on investments, change of control provisions and provisions as a percentage of total assets to be disposed off					20.00%
Notes Agreement \| Maximum
Credit arrangements
Principal amount		$ 75.0
Credit Agreement
Credit arrangements
Maximum borrowing capacity										$ 200.0	$ 125.0
Debt issuance costs									$ 0.6
Additional Period to Issue Notes		3 years
Available borrowing capacity								$ 4.0
Credit Agreement \| Federal funds rate
Credit arrangements
Basis spread on variable rate (as a percent)					0.50%
Credit Agreement \| Minimum
Credit arrangements
Prepayment to be paid on debt					$ 5.0
Restrictions on investments, change of control provisions and provisions as a percentage of total assets to be disposed off					20.00%
Credit Agreement \| Revolving credit facility
Credit arrangements
Maximum borrowing capacity								200.0
Maximum borrowing capacity with accordion feature								250.0
Borrowings outstanding								170.0
Credit Agreement \| Commercial letters of credit
Credit arrangements
Commercial letters of credit outstanding								26.0
Canadian Credit Facility
Credit arrangements
Available borrowing capacity							$ 7.5
Canadian Credit Facility \| Commercial letters of credit
Credit arrangements
Maximum borrowing capacity							$ 8.0
Commercial letters of credit outstanding								$ 0.5
Annual fee (as a percent)					1.00%
Canadian Credit Facility \| Commercial letters of credit \| Maximum
Credit arrangements
Term of credit facility					5 years