CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
CONSOLIDATED BALANCE SHEETS
Restricted investments in U.S. Treasury bonds-available for sale, amortized cost (in dollars)	$ 1,138	$ 107
Oil and gas properties, unproved properties excluded from amortization (in dollars)	$ 14,658	204,626
Restricted investments in U.S. Treasury bonds-available for sale, amortized cost (in dollars)		$ 962
8% convertible preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
8% convertible preferred stock, authorized shares	10,000,000	10,000,000
8% convertible preferred stock, issued shares	10,703	10,703
8% convertible preferred stock, outstanding shares	10,703	10,703
8% convertible preferred stock, aggregate liquidation preference (in dollars)	$ 128	$ 128
Preferred stock dividend rate (as a percent)	8.00%	8.00%
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, authorized shares	100,000,000	100,000,000
Common stock, issued shares	85,203,466	80,754,225
Accumulated other comprehensive income, applicable income taxes (in dollars)	$ 124	$ 141