Acquisitions (Schedule Of Final Values At The Date Of Acquisition) (Details) (USD $) In Thousands, unless otherwise specified			12 Months Ended				3 Months Ended
	Mar. 31, 2012	Dec. 31, 2011	Dec. 31, 2011 Lone Star Anchor Trucking, Inc [Member]	Dec. 31, 2011 Maverick [Member]	Dec. 31, 2011 Pat's P&A, Inc. [Member]	Dec. 31, 2011 Cryogas Services LLP [Member]	Mar. 31, 2012 Mayo Marrs Casing Pulling Inc [Member]	Mar. 31, 2012 SPA Victoria, LP [Member]
Business Acquisition [Line Items]
Closing Date			July 7, 2011	July 8, 2011	August 1, 2011	September 8, 2011	January 13, 2012	March 16, 2012
Total Cash Paid (net of cash acquired)	$ 18,610	$ 216,412	$ 10,102	$ 186,251	$ 8,974	$ 11,085	$ 6,644	$ 11,966