Significant Accounting Policies - Schedule of Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Earnings Per Share Reconciliation [Abstract]
Net (loss) income	$ (20,555)	$ 499,037	$ 26,933	$ 409,338	$ 177,140
Weighted average common shares outstanding - basic	197,054	180,964	196,803	130,770
Effect of dilutive instruments		69		308
Weighted average common shares outstanding - diluted	197,054	181,033	196,803	131,078
Net (loss) income per common share - basic	$ (0.10)	$ 2.76	$ 0.14	$ 3.13
Net (loss) income per common share - diluted	$ (0.10)	$ 2.76	$ 0.14	$ 3.12