Intangible Assets (Schedule Of Components Of Intangible Assets) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 393,274	$ 389,942
Accumulated Amortization	172,488	166,496
Carrying Value	220,786	223,446
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	94,654	94,654
Accumulated Amortization	87,153	86,285
Carrying Value	7,501	8,369
Licensing agreements
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	38,678	38,678
Accumulated Amortization	32,322	31,694
Carrying Value	6,356	6,984
Segment total
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	133,332	133,332
Accumulated Amortization	119,475	117,979
Carrying Value	13,857	15,353
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	35,430	35,430
Accumulated Amortization	32,452	32,044
Carrying Value	2,978	3,386
Intangibles associated with lease
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	13,260	13,260
Accumulated Amortization	4,104	3,986
Carrying Value	9,156	9,274
Segment total
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	48,690	48,690
Accumulated Amortization	36,556	36,030
Carrying Value	12,134	12,660
Marine contract intangibles
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	27,000	27,000
Accumulated Amortization	2,250	900
Carrying Value	24,750	26,100
Offshore pipeline contract intangibles
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	158,101	158,101
Accumulated Amortization	5,547	3,467
Carrying Value	152,554	154,634
Other
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	26,151	22,819
Accumulated Amortization	8,660	8,120
Carrying Value	$ 17,491	$ 14,699