Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Statement Of Financial Position [Abstract]
Joint interest billings and other, allowance	$ 163	$ 163
Office and other equipment, accumulated depreciation	$ 2,221	$ 1,600
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	20,000,000	20,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	22,575,052	22,289,177
Common stock, shares outstanding	22,559,695	22,273,820
Treasury stock, shares	15,357	15,357