Intangible Assets (Schedule Of Components Of Intangible Assets) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 395,363	$ 389,942
Accumulated Amortization	184,650	166,496
Carrying Value	210,713	223,446
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	94,654	94,654
Accumulated Amortization	88,888	86,285
Carrying Value	5,766	8,369
Licensing agreements
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	38,678	38,678
Accumulated Amortization	33,577	31,694
Carrying Value	5,101	6,984
Segment total
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	133,332	133,332
Accumulated Amortization	122,465	117,979
Carrying Value	10,867	15,353
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	35,430	35,430
Accumulated Amortization	33,268	32,044
Carrying Value	2,162	3,386
Intangibles associated with lease
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	13,260	13,260
Accumulated Amortization	4,341	3,986
Carrying Value	8,919	9,274
Segment total
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	48,690	48,690
Accumulated Amortization	37,609	36,030
Carrying Value	11,081	12,660
Marine contract intangibles
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	27,000	27,000
Accumulated Amortization	4,950	900
Carrying Value	22,050	26,100
Offshore pipeline contract intangibles
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	158,101	158,101
Accumulated Amortization	9,708	3,467
Carrying Value	148,393	154,634
Other
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	28,240	22,819
Accumulated Amortization	9,918	8,120
Carrying Value	$ 18,322	$ 14,699