Summary of Significant Accounting Policies - Earnings (Loss) Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accounting Policies [Abstract]
Net income (loss)	$ (259)	$ (5,506)	$ 20,733	$ (6,925)	$ 86,996	$ (22,006)	$ (31,068)	$ (12,764)	$ 8,043	$ 21,158	$ (68,989)
Weighted average number of common share outstanding — basic									25,568,371	24,630,898	24,266,407
Effect of dilutive share-based awards (in shares)									506,364	483,159	0
Weighted average number of common shares outstanding — diluted									26,074,735	25,114,057	24,266,407
Earnings (loss) per share:
Basic (in dollars per share)	$ (0.01)	$ (0.21)	$ 0.81	$ (0.28)	$ 3.50	$ (0.89)	$ (1.26)	$ (0.52)	$ 0.31	$ 0.86	$ (2.84)
Diluted (in dollars per share)	$ (0.01)	$ (0.21)	$ 0.79	$ (0.28)	$ 3.47	$ (0.89)	$ (1.26)	$ (0.52)	$ 0.31	$ 0.84	$ (2.84)
Antidilutive securities excluded									810,571	276,846
Antidilutive securities excluded from computation of earnings if not in net loss position											378,285