Supplemental Information (Supplemental Cash Flow Information) (Details 1) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Supplemental Cash Flow Information [Abstract]
Cash paid for interest, expensed	$ 137,950	$ 137,259	$ 151,831
Cash paid for interest, capitalized	77,432	60,540	66,815
Cash paid for income taxes	99,194	45,912	17,960
Cash received from income tax refunds	(38,004)	(24,677)	(15,107)
Non-cash investing activities:
Increase in asset retirement obligations	56,290	24,694	53,579
Increase (decrease) in liabilities for capital expenditures	(26,882)	74,697	(237)
Sale of non-core assets	(212,544)	0	0
Purchase of Thompson Field	212,544	0	0
Sale of Bakken area assets in Bakken Exchange transaction	(1,621,611)	0	0
Purchase of properties in Bakken Exchange Transaction	571,596	0	0
Issuance of Denbury common stock in connection with the Encore Merger	0	0	2,085,681
Vanguard common units received as consideration for sale of ENP	0	0	93,020
Restricted cash	1,050,015	0
Cash received in Bakken Exchange Transaction	281,669	0	0
Bakken Exchange Transaction [Member]
Business Acquisition [Line Items]
Fair value of net assets transferred	$ 1,903,280