Commitments And Contingencies (Narrative) (Details) (USD $)		0 Months Ended	12 Months Ended												6 Months Ended
	Jun. 30, 2013	Jun. 08, 2011 Robins Case [Member] claim	Dec. 31, 2010 Wunstell Action [Member] plaintiff	Dec. 31, 2011 Darnell Alexander [Member] claim	Dec. 31, 2010 Prejean [Member] claim	Dec. 31, 2012 Abney Litigation [Member] claim	Dec. 31, 2012 HEPACO Litigation [Member]	Jun. 30, 2013 Offshore Support Vessels [Member] equipment	Jun. 30, 2013 Inland River Liquid Tank Barges [Member] equipment	Jun. 30, 2013 Inland River Towboats [Member] equipment	Jun. 30, 2013 Harbor Tugs [Member] equipment	Jun. 30, 2013 U.S.-flag Harbor Tugs [Member]	Jun. 30, 2013 Very Large Gas Carrier [Member] equipment	Jun. 30, 2013 Other Machinery and Equipment [Member]	Jun. 30, 2013 Dorian LPG [Member] Subsequent Event [Member]	Mar. 31, 2012 Aviation Services [Member]
Loss Contingencies [Line Items]
Total unfunded capital commitments	$ 150,100,000							$ 128,200,000	$ 2,900,000	$ 10,900,000		$ 1,600,000		$ 6,500,000
Unrecorded Unconditional Purchase Obligation, Maximum Quantity								17	2	5	1		2
Partners' Capital Account, Contributions, Cash															42,100,000
Partners' Capital Account, Contributions, Noncash															14,900,000
Purchase commitments payable during the period	55,600,000
Unrecorded Unconditional Purchase Obligation Balance Sheet Amount Potential Amount To Reduce Liability																139,400,000
Number of claims company did not attempt to dismiss		1
Additional individual civil actions filed			2	117	3	668
Loss Contingency, Damages Sought, Value							$ 20,291,178.92