CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY Statement - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings
Balance at beginning of period at Dec. 31, 2012	$ 578,518	$ 40	$ 519,426	$ 59,052
Shares outstanding, beginning of period (in shares) at Dec. 31, 2012		40,115,536
Restricted common stock issued, net of excess income tax benefit (in shares)		310,439
Restricted common stock issued, net of excess income tax benefit	128		128
Restricted common stock forfeited (in shares)		(31,817)
Restricted stock used for tax withholdings	(4,440)		(4,440)
Restricted stock used for tax withholdings (in shares)		(108,239)
Stock-based compensation	12,638		12,638
Net income (loss)	69,184			69,184
Balance at end of period at Dec. 31, 2013	656,028	$ 40	527,752	128,236
Shares outstanding, end of period (in shares) at Dec. 31, 2013		40,285,919
Restricted common stock issued, net of excess income tax benefit (in shares)		309,458
Restricted common stock forfeited (in shares)		(31,597)
Restricted stock used for tax withholdings	(6,007)		(6,007)
Restricted stock used for tax withholdings (in shares)		(130,002)
Stock-based compensation	20,716		20,716
Stock issued upon acquisition of oil and gas properties (in shares)		853,492
Stock issued upon acquisition of oil and gas properties	49,051	$ 1	49,050
Net income (loss)	20,283			20,283
Balance at end of period at Dec. 31, 2014	740,071	$ 41	591,511	148,519
Shares outstanding, end of period (in shares) at Dec. 31, 2014		41,287,270
Restricted common stock issued, net of excess income tax benefit (in shares)		601,282
Restricted common stock issued, net of excess income tax benefit	1	$ 1
Restricted common stock forfeited (in shares)		(123,574)
Restricted stock used for tax withholdings	(2,683)		(2,683)
Restricted stock used for tax withholdings (in shares)		(108,070)
Restricted common stock forfeited	(1)	$ (1)
Sale of common stock (in shares)		8,050,000
Sale of common stock	202,688	$ 8	202,680
Issuance of common stock (in shares)		47,500
Issuance of common stock	326		326
Stock-based compensation	14,552		14,552
Net income (loss)	(745,547)			(745,547)
Balance at end of period at Dec. 31, 2015	$ 209,407	$ 49	$ 806,386	$ (597,028)
Shares outstanding, end of period (in shares) at Dec. 31, 2015		49,754,408