Intangible Assets (Schedule Of Components Of Intangible Assets) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 394,801	$ 389,942
Accumulated Amortization	178,527	166,496
Carrying Value	216,274	223,446
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	94,654	94,654
Accumulated Amortization	88,021	86,285
Carrying Value	6,633	8,369
Licensing agreements
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	38,678	38,678
Accumulated Amortization	32,949	31,694
Carrying Value	5,729	6,984
Segment total
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	133,332	133,332
Accumulated Amortization	120,970	117,979
Carrying Value	12,362	15,353
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	35,430	35,430
Accumulated Amortization	32,860	32,044
Carrying Value	2,570	3,386
Intangibles associated with lease
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	13,260	13,260
Accumulated Amortization	4,223	3,986
Carrying Value	9,037	9,274
Segment total
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	48,690	48,690
Accumulated Amortization	37,083	36,030
Carrying Value	11,607	12,660
Marine contract intangibles
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	27,000	27,000
Accumulated Amortization	3,600	900
Carrying Value	23,400	26,100
Offshore pipeline contract intangibles
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	158,101	158,101
Accumulated Amortization	7,628	3,467
Carrying Value	150,473	154,634
Other
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	27,678	22,819
Accumulated Amortization	9,246	8,120
Carrying Value	$ 18,432	$ 14,699