Net Income (Loss) per Share of Common Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Numerators for earnings per share:
Net income (loss) that is available to common shareholders	$ 16,719	$ 13,758	$ 34,225	$ (14,794)
Denominator for basic earnings per share:
Weighted average shares outstanding	21,796,172	21,799,782	21,816,323	21,667,408
Denominator for diluted earnings per share:
Effect of stock options and restricted stock units	402,536	440,531	452,161	0
Adjusted weighted average shares and assumed conversions	22,198,708	22,240,313	22,268,484	21,667,408
Basic earnings (loss) per share	$ 0.77	$ 0.63	$ 1.57	$ (0.68)
Diluted earnings (loss) per share	$ 0.75	$ 0.62	$ 1.54	$ (0.68)
Net loss position (excluded from denominator)
Shares excluded from diluted earnings (loss) per share due to:
Antidilutive securities excluded from diluted earnings per share	0	0	0	458,658
Inclusion would have been anti-dilutive (excluded from calculation)
Shares excluded from diluted earnings (loss) per share due to:
Antidilutive securities excluded from diluted earnings per share	127,258	192,090	97,951	151,732