Change In Accounting Estimate (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015
Change In Accounting Estimate [Abstract]
Period between salvage value reviews	3 years
Period used to determine reasonableness of salvage values	3 years
Decrease in salvage values	$ 0.6ish_DecreaseInSalvageValues

The length of time for the most recent average price of scrap steel per metric ton used as a basis for the determination of the reasonableness of current salvage values.

No definition available.

Name:	ish_PeriodUsedToDetermineReasonablenessOfSalvageValues
Namespace Prefix:	ish_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration