Business Segment Information (Summary Of Financial Data By Segment) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Segment Reporting Information [Line Items]
Revenues	$ 232,178	$ 197,461	$ 429,607	$ 427,303
Income (loss) from operations	47,197	6,869	62,435	56,937
Equity in earnings of investments	683	5,748	1,293	6,155
Contracting Services [Member]
Segment Reporting Information [Line Items]
Revenues	225,356	209,557	423,410	454,101
Income (loss) from operations	47,600	19,223	86,904	78,347
Production Facilities [Member]
Segment Reporting Information [Line Items]
Revenues	24,174	19,963	44,567	39,985
Income (loss) from operations	14,643	9,882	25,828	19,931
Intercompany Elimination [Member]
Segment Reporting Information [Line Items]
Revenues	(17,352)	(32,059)	(38,370)	(66,783)
Income (loss) from operations	(839)	98	(2,559)	(2,922)
Corporate [Member]
Segment Reporting Information [Line Items]
Income (loss) from operations	$ (14,207)	$ (22,334)	$ (47,738)	$ (38,419)