Business Acquisitions (Narrative) (Details) (USD $)	9 Months Ended			9 Months Ended			9 Months Ended						12 Months Ended
	Sep. 30, 2012		Dec. 31, 2011	Sep. 30, 2012 Wind Farm Utility Vessel [Member] equipment	Jun. 25, 2012 Pantagro Acquisition [Member] [Member]	Mar. 30, 2012 Superior Energy Services, LLC [Member]	Sep. 30, 2012 Superior Energy Services, LLC [Member] Liftboats [Member]	Feb. 01, 2012 ICP Acquisition [Member]	Mar. 31, 2012 Lewis & Clark Acquisition [Member]	Dec. 31, 2011 Lewis & Clark Acquisition [Member]	Jul. 09, 2012 Windcat Acquisition [Member]	Dec. 22, 2011 Windcat Acquisition [Member]	Dec. 31, 2011 Windcat Acquisition [Member] Wind Farm Utility Vessel [Member] equipment	Dec. 21, 2011 Naviera Acquisition [Member]	Jul. 29, 2011 Soylutions Acquisition [Member]	Dec. 22, 2011 Common Stock [Member] Windcat Acquisition [Member]
Business Acquisition [Line Items]
Number Of Equipments Delivered				1			18						29
Purchase price of acquisition	$ 148,673,000	[1]			$ 400,000	$ 142,500,000		$ 9,100,000		$ 29,600,000		$ 22,100,000		$ 1,900,000	$ 11,900,000
Business Acquisition, Cost of Acquired Entity, Cash Paid					200,000							21,500,000
Business Acquisition, Cost of Acquired Entity, Equity Interests Issued and Issuable											585,000					0
Common Stock, Par or Stated Value Per Share	$ 0.01		$ 0.01
Business Acquisition, Cost of Acquired Entity, Liabilities Incurred					200,000
Equity Method Investment, Ownership Percentage					95.00%			70.00%				75.00%
Business acquisition goodwill									1,600,000					1,000,000
Controlling interest obtained														70.00%	100.00%
Cash acquired from acquisition	$ 3,700,000

[1] Purchase price is net of cash acquired of $3.7 million and includes issued Common Stock valued at $0.6 million.