Long-Term Debt (Narrative) (Details) (ING Bank [Member], USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2013	Sep. 30, 2013
ING Bank [Member]
Line of Credit Facility [Line Items]
Deposit in association with covenant	$ 9.8
Approximate amount of deposit that will be returned due to increased vessel valuations		$ 7.3

Amount of deposit made in association with a covenant with a financial institution during the period.

No definition available.

Name:	ish_DepositInAssociationWithCovenant
Namespace Prefix:	ish_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration