Summary of Significant Accounting Policies (Details Textual) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013 Partnership	Jun. 30, 2012
Average Sales Price and Production Costs Per Unit of Production [Line Items]
Number of consolidated partnerships			42
Gas to oil conversion ratio (thousand cubic feet of natural gas per barrel of oil)			6
Percentage of discount factor applied to estimated future net revenues from proved oil and gas reserves			10.00%
Non-cash impairment expense		$ 9,909		$ 15,407
Cost method investments, additional information			The cost method of accounting is used for investments in affiliates in which the Company has less than a 20% of the voting interests of a corporate affiliate or less than a 5% interest of a partnership or limited liability company and does not have significant influence.
Equity method investment, additional information			If the Company holds between 20% and 50% of the voting interest in non-consolidated corporate affiliates or greater than 5% of a partnership or limited liability company and exercises significant influence or control, the equity method of accounting is used to account for the investment.
Anti-dilutive common stock equivalents excluded from calculation	2.7	4.9	2,700,000.0	4,900,000.0
Oil [Member]
Average Sales Price and Production Costs Per Unit of Production [Line Items]
Average sales price per unit			91.60
Natural Gas [Member]
Average Sales Price and Production Costs Per Unit of Production [Line Items]
Average sales price per unit			3.42
Nytis USA [Member]
Summary of Significant Accounting Policies (Textual)
Percentage of ownership interest in the subsidiary			100.00%
Nytis LLC [Member]
Summary of Significant Accounting Policies (Textual)
Percentage of ownership interest in the subsidiary			99.00%