Business Segment Information (Schedule Of Total Assets By Reportable Segment) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Total consolidated assets	$ 5,686,191	$ 5,702,592
Offshore pipeline transportation
Segment Reporting Information [Line Items]
Total consolidated assets	2,545,979	2,575,335
Refinery services
Segment Reporting Information [Line Items]
Total consolidated assets	395,147	395,043
Marine transportation
Segment Reporting Information [Line Items]
Total consolidated assets	804,706	813,722
Supply and logistics
Segment Reporting Information [Line Items]
Total consolidated assets	1,889,752	1,875,403
Other assets
Segment Reporting Information [Line Items]
Total consolidated assets	$ 50,607	$ 43,089