Business Segment Information (Intercompany Segment Assets) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Assets	$ 3,711,957	$ 3,582,347
Contracting Services [Member]
Assets	2,215,076	2,006,065
Production Facilities [Member]
Assets	509,468	534,776
Oil and Gas [Member]
Assets	$ 987,413	$ 1,041,506