Summary of Significant Accounting Policies - Earnings (Loss) Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accounting Policies [Abstract]
Net income (loss)	$ 86,996	$ (22,006)	$ (31,068)	$ (12,764)	$ (63,688)	$ (867)	$ (919)	$ (3,515)	$ 21,158	$ (68,989)	$ 12,324
Weighted average number of common share outstanding — basic									24,630,898	24,266,407	24,031,533
Effect of dilutive share-based awards (in shares)									483,159	0	705,428
Weighted average number of common shares outstanding — diluted									25,114,057	24,266,407	24,736,961
Earnings (loss) per share:
Basic (in dollars per share)	$ 3.50	$ (0.89)	$ (1.26)	$ (0.52)	$ (2.62)	$ (0.04)	$ (0.04)	$ (0.15)	$ 0.86	$ (2.84)	$ 0.51
Diluted (in dollars per share)	$ 3.47	$ (0.89)	$ (1.26)	$ (0.52)	$ (2.62)	$ (0.04)	$ (0.04)	$ (0.15)	$ 0.84	$ (2.84)	$ 0.50
Antidilutive securities excluded									276,846		269,992
If Not In Net Loss Position, Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount										378,285