Summary Of Significant Accounting Policies (Inventory By Class) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Summary Of Significant Accounting Policies [Abstract]
Spare Parts Inventory	$ 3,253us-gaap_OtherInventoriesSpareParts	$ 3,968us-gaap_OtherInventoriesSpareParts
Fuel Inventory	3,967ish_FuelInventory	4,663ish_FuelInventory
Warehouse Inventory	2,540us-gaap_OtherInventoryWarehouse	2,691us-gaap_OtherInventoryWarehouse
Inventory	$ 9,760us-gaap_InventoryGross	$ 11,322us-gaap_InventoryGross

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

- Details

Name:	us-gaap_AccountingPoliciesAbstract
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 SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 6

-Article 5

Reference 2: 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

+ 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