NON-MONETARY EXCHANGE TRANSACTION (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Oct. 22, 2012
NON-MONETARY EXCHANGE TRANSACTION [Abstract]
Number of existing vessels replaced with newer vessel		1
Cash paid in replacement of existing vessel with newer one	$ 3.7
Gain on replacement of assets	$ 12.2

The gains (losses) included in results of operations resulting from the replacement of assets.

No definition available.

Name:	ish_GainLossOnReplacementOfAssets
Namespace Prefix:	ish_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration