Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Numerator:
Net income (loss) used for calculation of basic and diluted EPS	$ 47,165	$ (8,868)	$ 40,767	$ (15,312)
Denominator:
Weighted average common shares outstanding, basic	40,800,586	40,389,648	40,703,688	37,518,271
Dilutive effect of stock options	937,874		997,574
Weighted average common shares outstanding, diluted	41,738,460	40,389,648	41,701,262	37,518,271
Net income (loss) per common share, basic (in dollars per share)	$ 1.16	$ (0.22)	$ 1.00	$ (0.41)
Net income (loss) per common share, diluted (in dollars per share)	$ 1.13	$ (0.22)	$ 0.98	$ (0.41)