Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Numerator:
Net loss attributable to common stockholders	$ (6,885)	$ 47,165	$ (21,519)	$ 40,767
Denominator:
Weighted average common shares outstanding, basic	46,767,759	40,800,586	46,683,744	40,703,688
Dilutive effect of stock options		937,874		997,574
Weighted average common shares outstanding, diluted	46,767,759	41,738,460	46,683,744	41,701,262
Net income (loss) per common share, basic (in dollars per share)	$ (0.15)	$ 1.16	$ (0.46)	$ 1.00
Net income (loss) per common share, diluted (in dollars per share)	$ (0.15)	$ 1.13	$ (0.46)	$ 0.98