Business Segment Information (Summary Of Identifiable Assets) (Details) (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010
Total assets	$ 3,552,009	$ 3,592,020
Contracting Services [Member]
Total assets	1,871,004	1,856,016
Production Facilities [Member]
Total assets	513,586	512,990
Oil and Gas [Member]
Total assets	$ 1,167,419	$ 1,223,014