Commitments And Contingencies (Narrative) (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2013 claim	Dec. 31, 2012 claim	Dec. 31, 2011 claim	Dec. 31, 2010 claim	Jun. 30, 2016 USD ($) equipment
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation, Due in Remainder of Fiscal Year						$ 142,304,000
Unrecorded Unconditional Purchase Obligation, Due in Second Years						93,329,000
Unrecorded Unconditional Purchase Obligation, Due in Third Year						41,603,000
Unrecorded Unconditional Purchase Obligation Due in Fourth Year						10,124,000
Unrecorded Unconditional Purchase Obligation						$ 287,360,000
Multi-district Litigation [Member]
Loss Contingencies [Line Items]
Claims Filed | claim					1
Loss Contingency, Number of Plaintiffs	11
Alexander Action [Member]
Loss Contingencies [Line Items]
Claims Filed | claim			410	117
Abney Litigation [Member]
Loss Contingencies [Line Items]
Claims Filed | claim			668
Abood Litigation [Member]
Loss Contingencies [Line Items]
Claims Filed | claim		174
Offshore Support Vessels Fast Support [Member]
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation, Maximum Quantity | equipment						9
Offshore Support Vessels Supply [Member]
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation, Maximum Quantity						0
Wind Farm Utility Vessel [Member]
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation, Maximum Quantity | equipment						1
U.S.-flag Product Tankers [Member]
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation, Maximum Quantity | equipment						2
U.S. Flag Articulated Tug-Barge [Member]
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation, Maximum Quantity | equipment						1
U.S.-flag Harbor Tugs [Member]
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation, Maximum Quantity | equipment						2
Inland River Dry Cargo Barges [Member]
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation, Maximum Quantity						50
Inland River Towboats [Member]
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation, Maximum Quantity | equipment						3
Offshore Marine Services [Member]
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation, Due in Remainder of Fiscal Year						$ 33,033,000
Unrecorded Unconditional Purchase Obligation, Due in Second Years						41,683,000
Unrecorded Unconditional Purchase Obligation, Due in Third Year						41,603,000
Unrecorded Unconditional Purchase Obligation Due in Fourth Year						10,124,000
Unrecorded Unconditional Purchase Obligation						126,443,000
Offshore Marine Services [Member] | Offshore Support Vessels Supply [Member]
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation, Contingent Upon a Third Party Option						$ 14,200,000
Unrecorded Unconditional Purchase Obligation, Contingent Upon a Third Party Option, Maximum Quantity						1
Shipping Services [Member]
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation, Due in Remainder of Fiscal Year						$ 82,825,000
Unrecorded Unconditional Purchase Obligation, Due in Second Years						23,624,000
Unrecorded Unconditional Purchase Obligation, Due in Third Year						0
Unrecorded Unconditional Purchase Obligation Due in Fourth Year						0
Unrecorded Unconditional Purchase Obligation						106,449,000
Inland River Services [Member]
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation, Due in Remainder of Fiscal Year						24,723,000
Unrecorded Unconditional Purchase Obligation, Due in Second Years						28,022,000
Unrecorded Unconditional Purchase Obligation, Due in Third Year						0
Unrecorded Unconditional Purchase Obligation Due in Fourth Year						0
Unrecorded Unconditional Purchase Obligation						52,745,000
Illinois Corn Processing LLC [Member]
Loss Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation, Due in Remainder of Fiscal Year						1,723,000
Unrecorded Unconditional Purchase Obligation, Due in Second Years						0
Unrecorded Unconditional Purchase Obligation, Due in Third Year						0
Unrecorded Unconditional Purchase Obligation Due in Fourth Year						0
Unrecorded Unconditional Purchase Obligation						$ 1,723,000