Net Income (Loss) Per Share (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Net Income (Loss) Per Share [Abstract]
Net income (loss) used for calculation of basic and diluted EPS	$ 40,464,000	$ (21,376,000)	$ 10,101,000	$ 23,753,000
Basic weighted average number of common shares (in shares)	34,616,197	30,059,329	34,560,021	29,739,326
Net income (loss) per share, basic	$ 1.17	$ (0.71)	$ 0.29	$ 0.80
Basic weighted average common shares outstanding (in shares)	34,616,197	30,059,329	34,560,021	29,739,326
Stock options and restricted stock units (in shares)	1,401,214	0	1,406,966	2,058,006
Weighted average shares outstanding, diluted	36,017,411	30,059,329	35,966,987	31,797,332
Diluted income (loss) per common share (in dollars per share)	$ 1.12	$ (0.71)	$ 0.28	$ 0.75
Stock options excluded from diluted EPS (in shares)	257,678	2,020,204	114,148	738,882