Significant Accounting Policies - Schedule of Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Earnings Per Share Reconciliation [Abstract]
Net income (loss)	$ (327,727)	$ 98,407	$ 81,611	$ 90,577	$ 56,151
Weighted average common shares outstanding - basic	196,331	80,003	152,864	79,991
Effect of dilutive instruments		381	204	370
Weighted average common shares outstanding - diluted	196,331	80,384	153,068	80,361
Net income (loss) per common share - basic	$ (1.67)	$ 1.23	$ 0.53	$ 1.13
Net income (loss) per common share - diluted	$ (1.67)	$ 1.22	$ 0.53	$ 1.13
Number of shares not included in dilutive earnings per share that would have been anti-dilutive because the exercise price was greater than the average market price of the common shares		262		756