Capital Lease Term

No definition available.

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- Definition

Capital Leases, Future Minimum Payments Due in Years Sixteen Through Twenty

+ References

No definition available.

+ Details

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Namespace Prefix:	cik0000750813_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

[Line Items] for Schedule of Capital and Operating Leased Assets [Table]

+ References

No definition available.

+ Details

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- Definition

Amount before accumulated depreciation of leased physical assets used in the normal conduct of business to produce goods and services.

+ References

+ Details

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

- Definition

The total charge for the use of long-lived depreciable assets subject to a lease meeting the criteria for capitalization.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6455314&loc=d3e45014-112735

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 10
-Section 55
-Paragraph 40
-Subparagraph (Note 2)
-URI http://asc.fasb.org/extlink&oid=6584154&loc=d3e38371-112697

+ Details

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

Amount of rent expense incurred for leased assets, including but not limited to, furniture and equipment, that is not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_BalanceSheetLocationAxis=cik0000750813_PropertyAndEquipmentMember
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Lease Obligations (Details) $ in Millions		12 Months Ended
Lease Obligations (Details) $ in Millions	Apr. 30, 2002	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2017 CAD	Dec. 31, 2017 USD ($)
Schedule of Capital and Operating Leased Assets [Line Items]
Operating Leases, Rent Expense		$ 1.1	$ 1.1	$ 1.3
Term of capital lease (in years)	20 years
Future minimum annual payments due under sale leaseback from May 2017 until April 2022 \| CAD					CAD 452,340
Property and Equipment [Member]
Schedule of Capital and Operating Leased Assets [Line Items]
Assets recorded under capital lease obligations			2.8			$ 3.0
Accumulated depreciation related to assets under capital lease obligations			$ 1.8			$ 2.1