Inventory (Inventory by Major Classes) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Inventory [Abstract]
Spare Parts Inventory	$ 1,874	$ 1,930
Fuel Inventory	2,714	2,854
Warehouse Inventory	2,251	2,251
Total	$ 6,839	$ 7,035

Gross amount, as of the balance sheet date, of fuel held for future sale or to be used in manufacturing, servicing or production process.

No definition available.

+ Details

Name:	ish_FuelInventory
Namespace Prefix:	ish_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

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

- Definition

Gross amount, as of the balance sheet date, of merchandise, goods, commodities, or supplies held for future sale or to be used in manufacturing, servicing or production process.

+ References

+ Details

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

- Definition

Gross amount of components of assembled products that can be sold directly or indirectly through sales of assembled products.

+ 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 210.5-02.6)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 6
-Article 5

+ Details

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

- Definition

Gross amount of merchandise, goods, commodities, or supplies held by the entity in a building or part of a building for future sale.

+ 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 210.5-02.6(a))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 6
-Subparagraph a
-Article 5

+ Details

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