ACQUISITIONS (Details) (USD $)						1 Months Ended	12 Months Ended		1 Months Ended	12 Months Ended		3 Months Ended	12 Months Ended
	Jan. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Nov. 30, 2012 U.S. United Ocean Services, LLC Acquisition [Member]	Dec. 31, 2012 U.S. United Ocean Services, LLC Acquisition [Member]	Dec. 31, 2011 U.S. United Ocean Services, LLC Acquisition [Member]	Aug. 31, 2012 Frascati Shops, Inc. and Tower, LLC [Member]	Dec. 31, 2012 Frascati Shops, Inc. and Tower, LLC [Member]	Aug. 06, 2012 Frascati Shops, Inc. and Tower, LLC [Member]	Mar. 31, 2011 Dry Bulk [Member]	Dec. 31, 2011 Dry Bulk [Member]	Dec. 31, 2010 Dry Bulk [Member]	Mar. 25, 2011 Dry Bulk [Member]	Mar. 24, 2011 Dry Bulk [Member]
Business Acquisition [Line Items]
Acquisition date							Nov. 30, 2012			Aug. 06, 2012
Subsidiary ownership interest acquired (in hundredths)	25.00%			25.00%	25.00%	100.00%									100.00%
Number of handysize bulkers controlled by acquiree						2
Number of tug/barge units controlled by acquiree						4
Amount of total consideration						$ 115,000,000					$ 4,500,000
Cash payment included in purchase price						112,200,000					623,000
Assumption of Current Liability						2,700,000
Business combination cost of acquisition legal fees						1,800,000			40,000
Summary of the amounts recognized for assets acquired and liabilities assumed [Abstract]
Working Capital including Cash Acquired						8,512,000					18,000
Inventory						6,510,000					231,000
Property, Plant, & Equipment						60,037,000					3,411,000
Identifiable Intangible Assets						45,131,000					490,000
Total Assets Acquired						120,190,000					4,150,000
Misc. Payables & Accrued Expenses						(5,039,000)					(383,000)
Other Long Term Liability						(2,070,000)					(3,490,000)
Deferred Tax Liability											(453,000)
Total Liabilities Assumed						(7,109,000)					(4,326,000)
Net Assets Acquired and Liabilities Assumed						113,081,000					(176,000)
Working Capital Settlement						(2,738,000)
Total Consideration Transferred						(112,244,000)					(623,000)
Goodwill		2,700,000	0			1,901,000					799,000
Business acquisition, pro forma information [Abstract]
Revenues							329,079,000	385,938,000
Net earnings attributable to ISH							30,765,000	39,166,000
Net earnings per share attributable to ISH common stockholders [Abstract]
Basic (in dollars per share)							$ 4.28	$ 5.49
Diluted (in dollars per share)							$ 4.27	$ 5.46
Revenue attributable to acquiree							7,600,000
Percentage of consolidated revenue (in hundredths)							3.10%
Percentage of consolidated assets (in hundredths)							19.50%
Equity interest previously held by company (in hundredths)																50.00%
Number of Capesize vessels controlled by acquiree															1	2
Number of Handymax Newbuildings controlled by acquiree															1	2
Equity interest previously held by co-venturer (in hundredths)																50.00%
Number of former subsidiaries of acquiree transferred to co-venturer															2
Number of Capesize vessels transferred to co-venturer															1
Number of Handymax Newbuildings transferred to co-venturer															1
Number of subsidiaries of acquiree controlling remaining Capesize vessels and Handymax Newbuildings															2
Number of vessels controlled by acquirer															2
Appraised value of Capesize vessels												84,000,000
Book value of Capesize vessels												53,600,000
Fair value of intangible asset relating to time charter contracts in place												5,200,000
Percentage of total fair value discounted (in hundredths)												50.00%
Discount rate (in hundredths)												5.10%
Calculation of the gain on the previously held equity interest [Abstract]
Fair Value of Previously Held 50% Interest												32,700,000
Less: Book Value of Previously Held Interest												(14,400,000)
Gain on Previously Held 50% Interest												18,300,000
Additional ownership interest acquired (in hundredths)												50.00%
Calculation of bargain purchase gain [Abstract]
Fair Value of Net Assets Acquired												69,000,000
Less: Fair Value of Purchase Consideration												(35,800,000)
Less: Fair Value of Previously Held 50% Interest												(32,700,000)
Bargain Purchase Gain												500,000
Revenue													7,300,000	7,300,000
Net income													$ 2,000,000	$ 2,000,000