Equity-Method Investments (Narrative) (Details) (USD $) Share data in Millions, unless otherwise specified	0 Months Ended	12 Months Ended			1 Months Ended	10 Months Ended	12 Months Ended	1 Months Ended	2 Months Ended
	Apr. 17, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Mar. 31, 2011 Dynamic Offshore [Member]	Dec. 31, 2011 Dynamic Offshore [Member]	Dec. 31, 2012 Dynamic Offshore [Member]	Apr. 30, 2012 Dynamic Offshore [Member] SandRidge [Member]	Feb. 28, 2011 SPN Resources [Member]	Feb. 28, 2011 DBH [Member]
Schedule of Equity Method Investments [Line Items]
Percentage of limited partnership interest	10.00%	10.00%			10.00%
Equity-method investments			$ 72,472,000			$ 70,600,000
Earnings (losses) from equity-method investments, net		(287,000)	16,394,000	8,245,000		15,000,000	300,000		200,000	900,000
Revenue from equity-method investment						44,900,000	49,800,000		300,000	900,000
Receivable from Dynamic Offshore			9,800,000
Receivable from Dynamic Offshore related to oil and natural gas commodity sales and production			14,000,000
Share Issuable in Acquisition of Dynamic Offshore								51.6
Gain loss from Equity method investment		$ 17,880,000					$ 17,900,000